Why does the Alorium Sno M2 work on Arduino 1.8.19 but not Arduino 2.3.5?

Why does the Alorium Sno M2 work on Arduino 1.8.19 but not Arduino 2.3.5?

It likely uses deprecated function names/libraries that are no longer the same in the new version of the IDE

I keep 2 separate arduino installations on my PC just for stuff like this (a 1.8x and 2.3x), this might work for you too (or a spare laptop/PC to just use the older version on)