I don't think I've read any reports of fans actually going on, or maybe slightly, but I haven't read every anecdote out there. I have trouble making the Mini warm, and other than the first boot, it's been silent and cool. I haven't been able to do an actual project since I got it set up, but I hope to do one this month.
Late 2015 27" iMac, i7, 4ghz, 32 gb RAM, OS 10.14.6, Logic Pro 10.5.1, 2020 M1 Mini, 11.4, Logic 6.2, RME FF802, Novation 61SL Mk II. Martins and Fenders and Gibsons, oh my!