That is interesting, because the following line in your log:
2023/08/31 15:07:17 ERROR : - Path1 file not found in Path2 - Documents/!JOT/Book/images/300px-Schrödinger_cat.png
indicates that bisync sees the file only in Path1, not Path2.
I notice that some parts of that log were redacted (replaced by <snip>) -- are you able to say whether there was another line similar to this one, but with the paths reversed? I ask that specifically because I notice that this particular filename has a special character in it (ö) and I'm wondering if somehow that character is being represented differently on the two remotes, thus causing bisync to think they are different files. It could have something to do with unicode normalization, especially since it looks like you are using a fairly old version of macOS, and Mac is notorious for unicode normalization issues. (FWIW, I'm a Mac user myself and haven't run into encoding issues with bisync, but I'm using the latest OS version and it's possible the behavior is different in yours.)
One thing that could still be helpful -- any chance you still have the .lst-err files from the failed run in your cache directory? The default location on mac is /Users/YOURUSERNAME/Library/Caches/rclone/bisync. They should still be there unless you deleted them. If you still have them, could you paste the line containing 300px-Schrödinger_cat.png from both files (.path1.lst-err and .path2.lst-err)? It may give us clues as to why bisync thinks they are different.
It could also be helpful if you could run rclone lsl on both the Path1 and Path2 versions of the problematic file, and paste what comes back. i.e.:
rclone lsl ~/OneDrive/Documents/!JOT/Book/images/300px-Schrödinger_cat.png
rclone lsl remote_onedrive:Documents/!JOT/Book/images/300px-Schrödinger_cat.png