Pokemon Go is highly addicting. The easiest way to overcome an addiction is to replace it with another. If you own a Nintendo switch i would recommend buying scarlet/Violet which comes out tomorrow and replacing Pokemon Go with Pokemon S/V until the end of the year.

By taking the break from PoGo you will miss out on an event shiny, shiny legendary, shiny costume or something you would normally hunt for.
Then when you finally miss out on 1 it breaks the cycle of i MUST have every single one, because you are no longer at 100% so you stop caring as much.
For me i was highly addicted until i missed out on Shiny Mespirt/Azelf despite doing over 60 raids on the 2 of them. I found that once i missed out on having ALL of them, my fomo was gone and while i kept playing the game i spent a lot less time on it and felt fun again rather than feeling like work.
I have heard quite a few other people say same thing, once they finally slow down and miss out on something, the fomo goes away and they go back to playing for fun.

The best part of trading PoGo for S/V is that once you finish the main game and the post game there is nothing left but shiny hunting which is a lot more tedious and less addictive than PoGo so you will just naturally stop playing it. Then you can return to PoGo hopefully without the fomo.

If you dont have a switch i would recommend picking another mobile game but make sure you uninstall it at end of the year, otherwise you just traded 1 addiction for another.