Hey Ole, just a few remarks.
- I have a lot of these coins from Guatemala and I absolutely don't believe in the dark/bright look because of the difference in Mint. These brass plated steel coins have the tendency of discoloring very quickly, because of the composition, not because of the Mint. Look at your 2023 coin: for a 2023 coin it really looks ugly.
- I know the bold/fine thing is your absolute pet peeve (I hope this is the right translation of the Dutch word “stokpaardje” because in English pet peeve has a negative connotation, something annoying or something you're complaining about a lot but I mean it like this, a pet peeve, figuratively speaking, is a subject someone is fond of and brings up again and again. It is a favorite pastime, and that's the bold/fine thing certainly for you). Unfortunately (and I know my eyes aren't that well anymore) I can't see any difference between your 2018 and 2022 coin (concerning bold/fine):

What I do see (besides the P touching/not touching a bead) is the distance between the “D” and the other lettering like “Paz” to the beads. The question is, are these differences because of the different Mint or because of the different date. As a varieties collector, you know especially Guatemala has the tendency of regularly making minor differences within a type. KM#'s 276, 277 and 278 all have 6 different subnumbers within 1 type. So we should focus on the 2023 coins because these are made both by Mint of Finland and Mint of Poland. If we can discover a difference there than we know it's because of the Mint and not because of the date.

I've got 33 of the 2023 coins. I'll try to make time today to study them and see if I can find a difference.
Let me know if you find out something about the KM# 248. I have a lot of them too:
