The one ui 5 is not fully optimised for Samsung's budget phones such as a53 and a73, so if you are planning on purchasing a Samsung midrange, get the pixel 6a instead.
Well if Samsung wishes to improve and optimize their UI for their phones then, I could change my mind.
It will get better overtime with software updates. There are things you can do such as wiping the phone cache partition after software updates as it is recommended to doing this for every update so that your phone doesn't have outdated files. It also fixes minor issues like lag stuttering and slow down. Use Device Care to regularly optimising your phone. Make the habit of regularly restarting your phone so it can be fresh. And cleaning the phone memory.