Magic Mouse With MacOS 26 - Tahoe when used in Safari

After trying everything - I just did a totally new reinstall of Tahoe to attempt to fix this issue and still no love. I wonder if there is a mouse driver issue - but it looks like I am on the latest firmware.

Here is the issue ...

Everything is fine with my trackpad BUT when I connect my Magic Mouse I have a singularly specific issue on any browser - Chrome, Safari and Firefox - go to (say) apple.com - and use the track pad to scroll down and it is as smooth as silk - use my Magic Mouse - I am wearing out my finger as it is almost as if I am paging down one scroll at a time. This is true on ANY browser (Chrome, Safari and Firefox) - whilst over in photos or pages or third party product - Craft - I do not have that issue - everything works beautifully. Any ideas? I have looked at Activity Monitor and killed all any any intensive processes - the problem never goes away.