it’s Tahoe’s new font window. and because sketchup still uses apple’s framework, we’re stuck with it.
bottom right, next to height, have you tried entering a size + pt ? (as in “15pt”)
you’re not the first one to report that, unfortunately, solutions are few, apple could change something again, sketchup might finally be released with the same UI as on windows, you could rollback to sonoma I guess…