There is always feedback. In general I judge my performance about how well I do compared to my coworkers in terms of output and what I know about my industry and what is "normal". I'm not the legendary 10x coder/engineer but I'm pretty good I think, in particular based on what I've done vs other people in terms of output and general reaction from peers (who i trust more on feedback than managers). I agree quite often "nice managers" will overdo it on praise, but there are other signs. You're not going to figure it out in a couple weeks, but I don't see how one can't get a general impression over a few months.