this
i used to play on ps3 years ago and it was always like that
you feel like your doing good win the first round and the next two they troll or just completely destroy you
i thought it would be different on pc but nope same old story
idk why i still play guess im just a masochist lol

can't demolish you if i don't know your habits

the first few games / rounds are referred to as 'downloading' by more competitive fighting game players, which basically means that people go "easy", or just slower on purpose, to judge your gameplan and the decisions that you make; once they think they've learned enough they can go on the offensive and use the information they gathered against you.

if you want to learn how to deal with a strategy like this try employing it yourself! it works really well for a reason, and if your opponent is giving you space on purpose, try using it against them by being more aggressive or clever as to not give them any proper information they can use
(Suegiclah explains this well in his own way too, check comments)

Its good to go easy on them to put them in positions so you can learn their weaknesses in the 1 round you will have until you demolish them, as an avid fighting game fan I find it really good to study my opponent as much as I can so I can take advantage of what I do know

It’s funny