No sir you're not the only one ...
I take it you know hoe to use the Device Maintenance app which will close any background apps and clear your ram on you're device? That can help allot.
Also make sure you use some of your storage on your device as virtual ram. Depending on the size of your device storage you can allocate up ro 8 gig of your storage as virtual ram and this definitely helps with slow device issues.
Finally I respectfully suggest you also use the Galaxy App Booster app on your S21 ultra this is also a great tool to tweet and boost your devices performance... Here's some screen shots for your information if you need it ... and please don't forget to report this issue through the error report section and allow your device to include a bug report so that the developers can address your issue
Kind regards


