The previous Syncthing version didn’t “work”, it just ignored this error, which didn’t have any consequences for you, as you don’t have symlinks in place.
It looks like the FindFirstFirstFile syscall is not supported with long path names on your driver (paths prefixed by \\?\).
See issue Watcher fails due to filepath.EvalSymlinks error (FindFirstFile) · Issue #5226 · syncthing/syncthing · GitHub and PR lib/fs: Try EvalSymlinks without '\\?\' prefix on failure (fixes #5226) by imsodin · Pull Request #5227 · syncthing/syncthing · GitHub