I’m running Fedora T2 + Cinnamon, because Fedora had a T2 version before Mint did, and because Cinnamon made it easier for me to block animation and increase font sizes than Gnome Classic did.
In Cinnamon’s “Font Selection,” I’ve set 20 point Roboto Slab.
In various “Authentication Required” dialogues, the text entry field sticks out the side of the window.
I’ve tested with 12 point Roboto Slab instead; but that’s small and hard for me to read.
In this case, it no longer sticks out, so I think it’s a mismatch between font size settings and window sizes.