Thank you for letting me know.
It's highly likely that the modifications to the registry settings and the installation of third-party apps are affecting the taskbar behavior, even after adjusting the scale.
I would suggest reverting the changes made to the registry settings and uninstalling any third-party apps that might have altered the taskbar. After doing so, restart your computer and check if the taskbar size returns to normal or responding to Scale change.
If you're unable to undo the registry changes, do you regularly back up your registry or have a system restore point set? You can use that.
If none please let me know.
John J.D.