Hi, I reply to this post because my ethernet adapter (brand "Uni" but with Realtek RTL 8153 inside) was working out of the box but was however not working after sleep. I always had to unplug / replug it on my MacBook Pro M1 to make it work.
I finally bought the "official" Belkin adapter from Apple web store and now it works after sleep. I checked in the system logs and, as said by different sources, the chipset inside this Belkin adapter is exactly the same as my previous one: Realtek RTL 8153.
So, beware, all RTL 8153 adapters do not seem to be working the same with Mac M1 / Big Sur!