The thickness of the digital “ink“ is different from older arc, but I really don’t see much difference in the proportions of Guts’ face from different angles in recent Episodes, at least none that are particularly significant (or more than the differences in older episodes).
The biggest inconsistency as such seems to me was just in the 2010s the style Guts’ face was drawn in evolved into a noticeably older look, possibly longer, definitely more gaunt, that I assume was meant to correspond to wear and tear from using the armor. It seems to me at some point Miura decided it was just making Guts look older than he intended the audience to perceive him as, and resolved to definitively go back to a younger look. Or it could be directly tied to his exhaustion levels in the story; I’d have to look. In any case, the flashback episodes almost felt like a refresher course for a younger Guts, and our present day one is getting a little meat back on his face.
And yeah a few panels here and there are a bit squashy, I’m not bothered. It IS funny though that Miura is more consistently careful about the shape of Guts’ ears than of his nose.