There are options to shrink it down if you wish. WinAeroTweaker has an option(along with a ton of other very useful tweaks) that let's you set the taskbar size to small.
Winaero Tweaker. The all-in-one app from Winaero. It will include almost all apps released by Winaero along with new tweaks and options. Windows Tweaker
winaero.com
This all looks like margin of error differences to me. Windows 11 is on par with 10 for gaming.
Unless the changes made in 11 are also made to 10. However, I'm willing to give them the benefit of the doubt. That video matches my experiences. None of the games I've tested run any worse on 11 than they did on 10. A few even run better. Whatever problems they had a few (beta)versions ago seem to have been resolved.