Some variables in program gets corrupted

A stack overflow seems rather improbable, spurious crashes would be more likely in this case.

Most probably this is caused by bugs in your (undisclosed) software. When hard-pressed for a guess, I would tend to an array index out-of-bound.

I am afraid if it happens in release mode also.

That depends on the differences between your debug- and release build, but I would bet so.

I would try data watchpoints. Support for those advanced debugging depends on your (undisclosed) toolchain and debug adapter.

Bravo to poster f.m. for his highlight of (undisclosed) code specifics and/or issue examples.

The entire code need not be presented - yet (some) illustrations/examples would seem an obvious aid to poster's forum "staff."

As presented - may I challenge your representation of being, "In the final stage of the project?"   With such multiple, undiagnosed, destructive issues I submit that you are FAR SHORT of (any) "Final Stage!"   Firm/I often note that such unresolved issues - left to fester to the, "final stage" - most always prove both difficult & expensive to find & correct.

KISS teaches that code should be modularized - properly/fully debugged & test/verified individually - and then (systematically & gradually) introduced to the full program.   As presented here - the identification of each/every issue has been rendered highly complex - and that (likely) could have been avoided.