The latest OS, I've not had an issue between operating system versions. I went onto my m1 mac from an intel long before I even knew I had some kind of issue and have used it comfortably ever since I bought it several years ago.
Current OS: MacOS Sequoia 15.4.1
Stillcolor: No, didn't even know about it until I had an issue with a newer M series mac with the display with the notch.
I did try it on all of the newer M series macs I mentioned that I had an issue with but it did not help at all.
Current iPhone 13 is on the latest OS too.
For me, I don't believe software has made much difference, i believe it's fully hardware but I'm not sure.
I have an M2 Pro Touch Bar 2022 on the way, a refurb, as I believe once the notch is introduced, I start having issues.
I'll update here. I'm hoping it buys me several more years for macs to work on to switch to a nicer screen for my eyes.
I rely on the portability, otherwise I'd just attach an m series mini to one of my monitors (VA) that I can use comfortably.