I totally second the OP in their concern. I must admit I felt some sort of satisfaction finding this thread so fresh, at the top of the list... what a perfect timing, purely coincidentally! I was just going to look for some UI Font Size feature requests to vote on.
The UI anti-aliased rendering of small text is terrible and barely usable. It might not be a problem if you are on an expert level and basically don't need to read what the UI says, but for beginners it means some horrible eyestrain.
I do graphics occasionally. Before, with Photoshop or Illustrator, I was more likely to get on an exploration whim once in a while, just for fun, to experiment with graphics. Today as I am on Affinity, the very thought of try to create a new personal avatar gets me those shivers of repulsion. Just because of the awful eyestrain association. (Well, the way/timing spacebar works for zoom contributes to it too)
Adjusting the UI Font Size to Large was the first thing I changed after my initial installation. It doesn't help much.
This hits me most in those text-rich preference screens where I need to lean almost into the screen to be able to read. And to be honest, when I switch momentarily to Default, I ask myself who's even able to think this setting would be a good starting point for anyone.
There's one more thing. For example, while the New Document screen is tabbable (the basic level of accessibility), most of the Settings sections are not. This also results in additional eyestrain on overload when you need to point your mouse to a precise point on a screen.
It's beyond my comprehension how one can do so inaccessible and unfriendly software these days. Seriously.