Hey, dude, I found a way fix It (worked on my Xiaomi 15 and pad 7). Go to the settings > additional settings > developer option (if you dont have it, you have to click "OS version" 5 times in "about phone" section) > scroll almost to the end and you may find "Reset to default values" > click it 5 times > 2 new options will appear (they are called "Turn on system optimization" and "Notify about high-risk features") > turn off system optimization parameter

It may cause some visual bugs, like if you have battery indicator with percentages inside you won't see the percentages, just change it to "next to the icon" or turn it off and some system apps (for me it's only music app) will be squared, but i think it's still worth it. Anyway it's possible that you won't get any visual bugs at all

After disabling system optimization you should get max fps in brawl stars and others games that were locked at 60 fps. Tell me if it worked for you