I honestly think you might just be "holding it wrong"... instead of zooming in on the text, can you try just moving your phone closer to your head and see if that helps? I honestly use old.reddit.com on mobile because the font size is better: I am not zooming in and out, and I appreciate being able to see more of the thread at once. The "mobile optimized" version of the site feels like I am being forced to have tunnel vision and it makes it really difficult to read anything.