Marketplace listings for bits are a lottery, a good share of them are counterfeits of the brand on the packaging, and wobble is exactly how that shows up in practice. Buy tools from a supplier that stocks the actual professional lines, and Staleks is the usual safe default for pushers and nippers, they hold up to repeated sterilizing far better than the generics do. I get mine from Nail Market USA https://www.nailmarket-usa.com/ along with files, and nothing has pitted so far. Check the shank size on your bits as well, because half the wobble complaints I see come down to a mismatch with the handpiece rather than a bad bit. Buy one of each shape first rather than a full set, most techs end up using three bits and leaving the rest in the drawer.