I just got: fpdebugdebugger.pas(4322,1) Error: Internal error 200602035 Even on a clean build.
(fpc 3.2.3, updated yesterday)

I am not able to create a small example, but I saved the state of my lazarus dir to
https://gitlab.com/martin_frb/lazarus/-/commits/fpc-err-internal-200602035 I hope this will reproduce.

In case it matters
-gh -g -gw3 -godwarfsets  -gl   -dCR   -Ct -Co -Cr -Ci  -gt   -Si- -Sa -dXe  -Se15  -ve -vw -vn  -vi
  -O-  -CX  -WC

Compiling the package fpdebug with the above details/commit should result in the error.

the error is caused by / line 426
     procedure DoProcessMessages; inline;

remove the inline and all is fine.

It may be noteworthy to mention line 4139
   ProcessMessagesProc := @DoProcessMessages;
The variable is in another unit.
var
   ProcessMessagesProc: procedure of object;