Fans running in sleep mode?

I have two Macbook Pros -- about two months ago both started getting incredibly hot when in sleep mode, running the batteries out completely if not plugged in (and when left charging, getting dangerously hot to the point it could be a fire hazard). I've tried everything to reset, including SMC resets for both, but nothing is remedying the issue. The 2018 is still running Ventura; the 2020 is now running Sonoma; both are fully updated. I've never had this issue prior to two months ago -- anyone know what's going on?