Hello everybody,
I am on the same boat and I am glad to know that I am not alone ... I've returned a macbook pro 13" 2020.
Forgive me for the long message but I've done many tests and I think the story might be useful to understand better the issue we are talking about in this thread.
I am the owner of an old MBP late 2009 13" (Yosemite as OS), which doesn't give me any eye problem. Maybe it sounds crazy but it still perfectly does its job (for most of the time, I use it for software development, writing code with BBedit) but I wanted to replace it mainly for security reasons (I can't upgrade to the latest OSs) and also to get better performances.
I was happy to see that Apple fixed the keyboard issues so I bought a MBP 2020; it looked amazing but then I realized it had two problems:
1) If I connected it to an external 1080p monitor, text looked blurry respect to what I saw with the MBP 2009 (same monitor). It was a very old monitor so I tried a brand new, expensive, eizo (still 1080p): same thing. Talked with apple support several times (apart from one guy, the support I received was terrible), changed many settings but I couldn't fix the problem.
2) After a few days, I realized that when I worked on the new MacBook (using its own display) my eyes got tired very fast.
Of course I changed the resolution (it sounds crazy to me that the default resolution is not the native one) and I tried many other settings but nothing solved the problem.
I have been using f.lux for many years on my MBP 2009 and I loved it ... on the MBP 2020 it just increased my eye strain.
At the beginning I though the main reason was the retina display (the high resolution), but I felt there was something more, related to brightness and colors.
The display for me is just too bright, too "shiny" ... it seems it has been made to impress potential customers on a store, playing a movie, more than to use it for hours, handling text (in fact, I had no problems watching a video).
You might think I could just decrease the brightness: no, it doesn't work, my feeling is that white and some other colors are just too bright and annoying for the eyes respect to other colors .. if you decrease brightness until you get the right level for white, other colors are just too dark.
So I decided to return it and to buy one of the last non-retina MBP, a mid 2012, on ebay.
The computer is perfect, it runs catalina, performances are better than my MBP 2009 and the problem with the eye is less important than the one I experienced with the MBP 2020, but it hasn't disappeared.
Not sure if it depends on the video card, the display but if you look side by side the two MBPs (2009 and 2012) you see two very different things, the 2012 is much more shiny, colors are totally different, what you see on MBP 2009 is more grayish and at a first glance you might say it's worst, but it's definitely more gentle on my eyes.
I also did another test: I booted the MBP 2012 with a superduper disk containing a clone of the MBP 2009 disk ... that difference didn't disappear.
Maybe it's important to mention that I did a:
defaults write -g CGFontRenderingFontSmoothingDisabled -bool NO
on the MBP 2012 to make text rendering better, otherwise the problem was even worst.
I have always been sensitive to light, back at the end of the CRT era, even if I was in my early 20s, I used filters on the display and I couldn't stand more than a few minutes in front of a monitor having a low refresh rate or a non native resolution set.
My eyes, however, according to all the doctors who visited me, are ok, I have just a very very low astigmatism.
Other devices: I had iPhone 3gs, iPhone 5s, iPhone 8, no problems at all with any of them!
Between 5s and 8 I decided to give a chance to Android and I bought a Sony Xperia XZ1 .... terrible experience, I had to return it after a few days ( same feeling with the display I had with MBP 2020)
I have read all the thread and I am still not sure which is the factor(s) that impact more.
There is one thing I am sure about, though: if matte displays were still available, the problem would be less important. I clearly remember when I bought the 2009 macbook, matte displays were still around (only for 15" though, I needed a 13") and I compared two 15" MBPs, side by side, matte Vs. glossy ... there was no competition, the matte (from my point of view) was so much better for the eyes!
It's true that people affected by these problems are a minority, but if you start googling you will find tons of messages! So maybe we can really try to ask something to Apple (maybe through change.org?) related to this issue.
What do you think?