Not OP, but I've noticed the same with Linux over the past year or two. Stability has taken a distinct dive for the worse.

Two different Ryzen APU based computers I've built running whatever Ubuntu happened to be the latest. Tried both KDE and XFCE and they freeze about 1-2 times a week. The computers haven't crashed and if you ssh in everything seems to be running fine, but mouse/keyboard/screen are completely frozen. One computer dual boots Windows and I can run Windows for a month on it without rebooting and it never misses a beat.

When you ssh in is memory nearly exhausted because firefox or Chrome have decided to eat all your memory?

Not OP, but I run elementary OS 5.1.7 Hera, built on Ubuntu 18.04.4 LTS, Linux 5.4.0-65-generic.

Its more stable than it used to be, but the desktop manager still keeps hanging every fortnight or so. Changing the brightness, right after unlocking my laptop is a recipe for getting frustrated, and eventually having to hard restart the computer. Other micro issues pop up every now and then.

Basically every laptop is unsupported or best effort / best luck on Linux (except System 76 and the like.) My brightness control keys use to work or not according to the kernel and the NVIDIA driver versions. I configured two hotkeys to increase and decrease backlightining with X11 and forgot about the original ones. However I never got a crash because of them. Maybe the screen froze a couple of times since Ubuntu 20.04, probably a video card crash (lots of windows.)

Oh I didn't install (on purpose) the NVIDIA drivers in my computer this time around. Last time, the brightness control would stop working, and the GPU would run a 100% of the time my computer was on. Drained battery in about 45 minutes.