I've been actively playing TF2 since Day One, and it pains me to rate this game negatively but here we go.

Valve need to fix majors issues such as:

1-Solve cheats / bots related problems. Sue nasty individuals hosting cheats and bots on their websites. Forgot your own Steam rules, Valve?
https://steamproxy.net/steamstore/online_conduct/?l=english&snr=2_groupannouncements_detail_

2-Use permabans when needed. Most cheaters have total impunity these days. Some of them are well known in the community and ruined TF2 for a decade.

3-Update your VAC system because this is an outdated piece of crap by today's standards.

4-Stop neglecting TF2.

- - -

Now let's talk about few things:

Competitive Mode:

Remove it completely. Noboby plays it.
The unofficial "comp scene" have his own set of rules/weapons restrictions and leagues. Everyone knows "comp players" don't use your official version of competitive TF2.
This is just pointless to keep that "dead on arrival" competitive gamemode in the main menu.

TF2 was never designed to be a competitive game at his core and it shows.
It just doesn't work.

Not to mention it's nearly impossible to balance every weapons for both Competitive Mode and Casual Mode.

And considering unofficial comp scene is a very small part of the TF2 Community, the game shouldn't be balanced towards this vision of the game. We need random bullet spread "On", random crits "On", and kept the fun aspect of some weapons, this is a part of TF2 DNA.

- - -

Casual Mode:
The name "Casual Mode" is so misleading. Why you may ask?:

First:
This is just "Team Fortress 2" with a bad name. Let me remind you, this game exist since 2007 and you can literally see any type of players in public servers these days, such as: veteran players, regular players, casual players or "fresh installs".

Second:
It was indeed called "Casual Mode" to make a differentiation with the Competitive Mode that nobody plays (as I explained above), and so the name "Casual Mode" never made sense to many (because TF2 is easy to learn BUT hard to master).

1-The Matchmaking:
It was doomed / broken since start. All you need to know is explained in this video.
https://www.youtube.com/watch?v=pRTLnJO3zeU

Create some sort of Quickplay 2.0 instead.

2-Class Restrictions:
Force 2 slots maximum per class, it should be beneficial on a 24 slots server (meaning every team have at least 1 merc of each type). It will helps to NOT have 3 Spy, 3 Sniper or 3 "whatever" class per team which leads to unbalanced / boring rounds.

3-Weapons Stats Changes:
A lot of buffs and nerfs are needed.
-Talk with the community about that. Share and explain any changes into the TF2 Blog (like it was the case few years ago, it was great).

4-Classes Changes:
Sniper:
-This is the only class in TF2 that can oneshot a merc with hitscan weapons AND he can do that AT ANY RANGE in a blink of an eye. Literally no other mercs have such power.
Also the Jarate + Bushwacka combo is way too good (you can kill 7 out of 9 classes in a single swing).

Razorback also deny any spy knives (which is the primary weapon of this class).
Sniper is supposed to be kinda weak at close range.

Demoman:
-"Hybrid Demoknights" are tolerable BUT "Full Melee Demoknights" should be removed because this subclass as nothing to do with a Demoman in general. I mean no explosives weapons on a Demoman? You can't take down a sentries nest reliably. No others subclasses for others classes redesign a class entirely. This is a literally a new class that add so many problems about the general balance of TF2. Totally absurd and HORRIBLE to fight against.

Engineer:
-Short Circuit on Payload Mode in BLU team is too good, you can spam it while being near the cart (and deny Soldier and Demoman primary weapons), because you've infinite ammo while pushing the cart).

Spy:
-Remove the "outline feature" for allies when they spawn for the enemy Spy.
This feature give the position and direction of any enemy Spy. We've been playing for years without this feature, and it wasn't a problem at all. This is literally a wallhack against Spy.

But this is only the highlights of the worst things, much more work is needed to balance this game properly.

5-Ranks:
For the people who accumulated XP points in Casual Mode since 2016 and still doing it to this day. You should update and create new ranks for the most dedicated players who already reached the max rank (Tier 8 Level 150) years ago. You can also create a new item with differents grades that reflect current XP points kinda like the badges for winning "Dueling Mini-Game", to not waste all the XP collected.

6-Community Fixes:
Plenty of fixes already exist and are "ready to use" in the TF2 Workshop.
Many of them makes so much sense and are extremely well made, all the good stuff should have been implemented since years.

And these dedicated people literally do your jobs for free. What are you waiting for? Make it happens...

- - -

Cosmetics, Maps and Content:
1-Adding 1 extra cosmetics slot?
Actually people want to equip all (or more of their items).
-One headgear, one facial misc, one upper body misc, and one lower body misc would make so much sense to fully equip your merc from head to toes.

2-Bringing back good and harsh quality control for the TF2 Workshop submissions?
So many questionnable cosmetics have been added officially into the game and started to ruin the iconic TF2 artstyle since few years. Take notes:
https://www.youtube.com/watch?v=8RAF-55O2-k

3-Stop adding truckload of unusual effects:
Most of them tends to ruin the TF2 artstyle and bloat this game even more.
Fun Fact: Nowadays you looks special when you don't wear unusuals...

4-Stop addind unfinished maps.
I mean pl_wutville was the worst map ever added officially in TF2.
Seriously what the heck...

5-Quality > Quantity
In 2023, 14 maps for Summer Update and 12 maps for Scream Fortress. 10 maps for Smissmas. 36 maps in 1 year. This game receive more maps this year alone, compared to the 5 previous years combined or something like that. Not to mention, half of them are bad/passable or broken on launch.

How about 2-3 very good maps per event maximum, it should be better and more than enough.

- - -

Scream Fortress:
-Halloween contracts are the same since 6 years. And "bonus contracts" are insanely tedious to do in some maps, especially the infamous "pumpkins bombs kills".

I know that because I was mad enough to completed them at 100% every year since their creation. it's getting old, boring AF and time consuming.

And even if you play with 5 friends, it takes longer each year since more maps are added. I would rather suggest to remove contracts entirely at this point in time. And no rewards for completing every bonus? What a joke. At least gave something for the players who completed them since 2018 (could be a specific medal or cosmetic). This is harsh...

- - -

Now:
TF2 is slowly dying since 2016 and TF2 players are fed up by all this bullsh.it.

1-The massive amount of cheaters and bots make this game unplayable.
Usually and in my experience 7/9 out of 10 games are ruined by bots and cheaters since 2016.

2-The lack of meaningful updates since 2017 / 2018 (Jungle Inferno and Blue Moon Update were the last majors updates).

3-Did you even remember what you said in response to the #SaveTF2 movement?
https://twitter.com/TeamFortress/status/1529970640224018433
We're now 2 years later and none of these issues have been addressed...

This is an ABSOLUTE SHAME to see this masterpiece of a game on a such AWFUL state.

Last but not least, seeing TF2 dying because of cheats and lack of attention BUT still being monetised while most of the content is made since years by the TF2 community is infuriating.

And seeing Valve that take the biggest portion of the revenues while doing nothing but ruining his own game is insane, especially when your loyal playerbase asked you to fix this game since ~2016. From best developpers to worst. Fu.cking sad.