A lot of people have been posting about more battery draining and slow performance since updating their phones to One UI 7.
There is a free Samsung app that helps optimise your phone after an update, and all the time!
It's normal and expected for your phone to run slowly or drain battery quickly after an update, as the apps need to optimise themselves to the updated OS.
The Good Guardians App is downloadable for free from the Samsung app store, and within it, is the galaxy app booster module, which is perfect for optimising your phone after an update!
If you have any other questions about the update, or Samsung phones in general, I'm quite tech savvy and have looked into it quite a bit, and discovered things myself, so comment your question and I'll do my best to try and help you!
See attached images.

They clearly tell you that it's perfect for this.

All available modules within the app (on a galaxy a16)