Yeah but that’s not the result of desktop class browsing vs mobile browsing. That’s the result of Safari text sizes and/or Macrumors text sizes getting tweaked, in a site that was already desktop class on the iPad.
Remember, if you go to Macrumors on an iPad in iOS 12, you get basically the same site as you get on a laptop or desktop. You do NOT get the mobile site like you get on iPhones.
You’re sort of missing my point. The SAME iPad mini renders text on this site differently on iOS 12 vs iOS 13. It absolutely is the case that iOS 13 now identifies itself to websites as a desktop computer as opposed to a tablet. Macrumors is designed as a “responsive” site and will serve up the version it deems most suitable based on the screen size of the device accessing it. Previously, it would serve up something suitable for a tablet. Now, at iOS 13’s request, it’s serving up something for a desktop and the text is being rendered differently. There may also be other optimizations Apple is also making under the hood. Net effect is that I now find an iPad mini useable whereas I previously would’ve agreed with you that text was way too small.