Seems to me that Safari is still a memory hog on Big Sur? Is that correct? Some websites I have used with Safari, tell me to close the page I am looking at to conserve memory.
This doesn't seem to be an issue when using Chrome.
Having similar issues - but I did read on another forum that unless you are actually experiencing computer lag problems due to RAM management, there is no need to worry about it (which made complete sense to me). I typically only get warnings on sites that have a metric sh*t ton of imbedded videos and adds (so annoying!), and typically close them out. I just don't like it when I'm reviewing sites for research papers and the memory warning keeps coming up. Can't always close them down. But when I considered what I mentioned about reading elsewhere - I never once did experience any perceptible "delay" or "lag" on the computer even when getting the warnings...
I have exactly the same problem, even worse, my Safari just randomly restarts after closing the message of using too much memory. I have Sensi running indicating that Safaris is ranked 5th in RAM usage and using less than 100MB. I have a brand new iMac 27 with 16GB Video Ram and 128GB Ram, so that isn't the problem. Safari 14 is a complete disaster. Nothing is faster than chrome and FireFox. (I refuse to use anything from Google)