They don't need humidity domes, they are not rainforest plants!
They need good air exchange to grow properly and a bit of air movement to strengthen the stem.
Humidity domes is an outdated notion from the 1960s when no one knew anything much about cannabis and thought it came out of jungles.
Unfortunately this idea has persisted, needlessly, until the present day.
I have never in close to 40 years, ever grown seedlings in humidity domes and firmly believe they are absolutely not needed.
Only cuttings/clones need humidity domes.