My nomination was accepted but its been 3 weeks did not appeared yet
Hello and welcome @patrickknows05
Unfortunately it is likely that the reason that it is not appearing is because although approved it has not been selected for Pokémon Go. This could be due to the distancing rules it uses.
This article explains S2 cells ( mapping software) which is what the selection rules are based on. 1 stop or gym in a level 17 cell.
https://pokemongohub.net/post/article/comprehensive-guide-s2-cells-pokemon-go/
If you could provide the location (co ordinates are best) and what it is we can have a look at some maps to see if that is what has happened - the information we have access to is unfortunately 5 months out of date so we not be able to say for sure.
It’s not always clear where you should posts and the section this should be in is nomination support so I have moved it there 