See https://www.eatortoss.com/how-to-tell-if-white-stuff-on-chee..., https://www.eatortoss.com/aged-cheddar-with-a-crusty-white-s....
The rule of thumb I've heard is hard white: crystal. Soft white: mold.
If you can't tell, I would dump it.
Now, that doesn't mean rando-mold doesn't ruin the cheese's flavor...
Sadly, the wayback machine has snapshots of the article going back to 2020, but doesn't seem to have archived those broken image links.
See https://www.eatortoss.com/how-to-tell-if-white-stuff-on-chee..., https://www.eatortoss.com/aged-cheddar-with-a-crusty-white-s....