Badge is a combination of 3 parts:

• Stars - number of units
  
• Shapes - number of tens
  
• Background - number of hundreds

Stars represent your number of units in level.
They repeat every 10 levels.

Stripes represent your number of tens in level.
They repeat every 100 levels.

Background represents your number of hundreds in level.
It has five shapes - they repeat every 500 levels, changing color.

Background changes are capped at level 1.900, but the highest level you can reach is 12.255, so stripes and stars will keep changing.


Level 12.255 badge

But, if we just combine all parts of the highest levels, we get this:


Level 1.999 badge

Level required to max all of your perks is 326.
(325 if you get Manipulation perk in Ryujin Industries questline)

After reaching level 10.000 your badge becomes like you are level 0.
This is the only way to see what level 0 badge looks like directly in the game without editing game files.


Level 0 badge

Level 10.000 resets your badge, so its appearance will repeat.
Trying to level up after level 11.476 will bring you straight to level 12.255 for some reason.