I'd be curious to hear about this too - I don't see any issues filed or commented on by him, perhaps the bugs are more perceptual mismatches with his React experience as opposed to actual bugs. We only recently released preact/debug, which brings with it some of the guardrails React ships by default - maybe without those people run into issues.
FWIW there are hundreds of companies (some very very large) using Preact in production. If there were showstopper bugs, they'd be fixed immediately.