Varieties on Thailand 25 satang - Rama IX

Hi,
I have 11 coins of this type. Five of them seem to have a "fatter" font and they are all from 2009. I have "thin font"-types from 2008, 2009 and 2010.
As I can't find any info on varieties for this coin, I'm wondering if it might also just be an optical illusion due to the wearing off of the lustre, though that would be weird that they're all from this same year.
https://en.numista.com/catalogue/pieces7973.html

Please have a look, can you find the difference?


Here the two (possible) varieties from 2009.



Thanks for looking
Bram

the fatter font could be because the die has worn out.
Or because the copper plating is thicker.