I sometimes receive review requests that says the authors have recommended me, and I know them in person but I have no COI, so I do my best to objectively evaluate their paper. Also, I do suspect some labs might be recommending me as I always end up reviewing their papers (or maybe the editor thinks I am a good fit, I don't know).
When I submit however, I feel this is not very appropriate. I don't mind reviewing for others who recommended me but I don't recommend anyone because I don't think it is ethical, but I have been having problems with the reviewers simply not having adequate expertise on the field, though they are quite arrogant so in the end I receive reviews that are low-quality (and I mean this, they are not just mean reviews or anything, I mean reviews that are technically dead wrong that they don't get the scope, methodology not even what problem is being solved) How common is it to recommend referees for your paper? Am I missing something?