Sorry. I don't use Brisa so not sure if this applies. I used to get a lot of probs like this when I first started using gel, but only on the right hand. Took me a long time to realise that when I'd finished buffing the right hand and moved onto the left, my client would be fiddling with the right hand, running her fingers over the buffed nails, running her fingers through her hair etc which would affect the finished product. So I now put the finishing gloss on the right hand and cure BEFORE I start buffing the left, and rarely get probs.
Could also be an uneven coverage of your UV gloss. When you have finished applying double check before you put them in the UV, use your overhead light as "your friend"! move the nails around so that the light will reflect back any dust bumps, uneven coverage and missed bits.
Could also be that you are not applying quite firmly enough so make sure that gel is really on the nail!
HTH