It looks like WIFI signal strength was significantly decreased in Big Sur. Now I can block the WIFI signal of my macbook pro by just putting my right hand on the side of the laptop - the same computer in the same spot had no WIFI issues when using an older O/S on the same early 2015 box. I can clearly see that using ping, for example, cover the USB/HDMI/card entry and signal is instantly lost. All other computers function on WIFI as before.

Debugging further, the issue looks to be defaulting on 5GHz WIFI network. Resetting to 2.4GHz puts things back close to normal. Not sure if there is interference with satellites (5.5GHz usually) or just being too far... Anyways, if you encounter this problem, make sure you check it on 2.4GHz, too.