I thought they were letters from another alphabet or something, had no idea they were just another font.
It’s the thing where similar-looking letters are taken from other alphabets to make fancy looking letters. The not-O there is a Greek letter, for example, specifically I think it’s lowercase Sigma.
Ironically, given Yog is a Russophone and people do this with Cyrillic all the time, much to the chagrin of those who can read Cyrillic.
A very mean, and sometimes fun, trick to play on others in a collaborative programming environment is to randomly replace semicolons with Greek question marks and watch them slowly descend into madness during debugging.