Yes, the case where you activate native start menu on one monitor but then close via activating app on another monitor seems to be bugged. How did you enable showing start menu via Win key on non-main monitor?
This sporadic fullscreen taskbar behavior is since Windows 2000, I don't believe it's fixed in Windows 11. If you're 100% certain it doesn't happen with native taskbar, please record shortest reproduction video.
https://www.startallback.com/download.php?v=3.9.1 (previous version number)
https://startisback.com/StartAllBack_setup.exe (test version)
Beta versions are purged and not preserved.
If you meant Windows 7 style in light mode, there's a variant with darkened active button https://startisback.com/Windows 7 active.msstyles though sloppy
New text 'Never group' is for 'Combine taskbar buttons:' combobox, so 'combine' must be not previously translated as 'group'. You may try better to explain three 'never' options.