For some reason My tech 2 science says Optimized Biome Planner instead of Single-use ATMOS set. Do I have a mod mistakenly installed? Or is there a mod I should downgrade?

Can you post a screenshot please? You should have both Optimized Biome Planner (aka bio science) as well as Single-use ATMOS Set (aka green science).

https://prnt.sc/Oo67_6VOsf4Q

I've selected circuit network which uses ATMOS but it show I need to input the biome planner.

You are using the first tier of lab. It can only take red and bio science. Upgrade your lab to the next tier.

Ty sir