Re: Apex Legends Anti-Cheat error gdiplus.dll not trusted
GDIPlus is a graphics library used by some Windows components and some 3rd party apps. There was a vulnerability issue some time ago, which could be exploited in different ways, and that's why EAC has flagged it. Although, EAC only looks for the particular version (and some older ones) of the file.
Removing it manually, and ONLY this file is fine, as long as you have the most recent Windows update, with the latest version of GDIPlus..I would recommend to Google "clean up WinSxS folder" first.