cant open the game in vanilla launch mode (and simply cannot open the game in steam)

ive gotten a lot of not repentogon mods, and one day i deleted well-known mod "antibirth++" for antibirth music and change it to its other version "antibirth+++". and my game stopped lauching. i tried to delete all mods from any game files, i tried to delete every single repentogon mention in game files, i thought that was the issue. but its all in a vain. so i finally open repentogon launcher. and isaac was able to open, but only in repentogon launch mode. tried in vanilla launch mode, it failed. there was this info in repentogon launcher:

[WARN] Game exited with error code 0xc0000409 (stack buffer overrun)
[WARN] Last few lines of the log.txt:
[WARN] -- START --
[WARN] [INFO] - Viewport: 1920x1080
[INFO] - Framebuffer Width: 1921
Render Width: 960
Window Width: 1921
Multiplier: 4.500010
DP per point: 1.000000
Point Scale: 2.000000
[INFO] - playing cutscene 1 (Intro).
[INFO] - Renderbuffer ID: 1 size 2048x2048
[INFO] - HQ4X size: 1921x1080
[WARN] -- END --
[WARN] Check log.txt and launcher.log for more details!

what does mean stack buffer overrun?

Start by reviewing log.txt and launcher.log, then compare the vanilla and REPENTOGON launch modes using the reported 0xc0000409 failure. Done would require a reproducible diagnosis and a clearly identified fix, but the report names no source file, test, or specific code change.