Firefox user and tab collector here.
I also use Lightroom(Classic) a lot. Before the M1 native version of LRc, it was basically unuseable on 8gb with anything else running in the background. The M1 native version does handle it better, but I've found it still slows everything down if I don't quit it before going back to doing something else. I never had to do that on the 2012 MBP with 16gb this computer(M1 MBP) replaced.
Firefox unchecked can easily grow to 10+gb and I need to restart it every day or two because it drags the system down so badly.
Docking and undocking seems to make memory use go through the roof and I don't know why.
Bottom line for me is I'm regularly seeing 80%+ memory pressure and I can't find any reasonable explanation for it. Even with fast swap, I can feel this bogging down the system. It was unusual doing the same sort of tasks on my 2012 MBP to hit ~60% compression, and that was even running a VM.
I do have a Mac Pro 5,1 with 96gb RAM, and OS X(High Sierra) doesn't seem to know what to do with that much. I can hit it in certain situations(manipulating huge film scans in Photoshop) but in general that's a difficult amount of RAM to use. 32gb is likely a sweet spot for me.
I'm planning on buying a Mac from the next generation of ARM(M1x or M2 or whatever) and I will get at least 16gb, more likely 32gb if I can. I managed 9 years out of my last primary Mac, and it was(and still is) perfectly useable. My M1 Pro won't make it that long, but I'm hoping the next gen will.