Just now, when reloading Stack Overflow on my mobile, the font sizes have been enlarged:
I'm aware that the mobile views are deprecated, but this change doesn't look intentional.
The font sizes increases from
20.9231px on question titles.
It's quite hard to see exactly how large the title gets compared to the other text; I'd recommend dragging your browser window to a mobile size to experience this yourself.
The best comparison I've got is from my open tabs on my phone:
Asking here as this seems platform-wide.