I’m trying to speedrun a mobile game but it has ads that pop now and again can I still speedrun this game

You can either

1. Use some kind of mobile adblocker
2. Disable your internet connection if it's an offline game

You have to be on wifi for some reason so I will try and adblocker

If you are asking if the run will be rejected if it has ads, check the rules to the specific game (although I've personally never seen a game that would reject a run just because it has ads)

I guess that calculating times of runs with ads can be difficult (unless the ads are factored in the total time).