or it would have been easier for Drizzly to to discover from a popular startup blog than from a not so popular stock artwork

It's just a traced vector of a bear. Again, as someone who is familiar with this process, if we were just going to steal something, we would have put a bit of effort into not looking stolen.

Even an amazing designer can't make a silhouette of a bear from memory and he probably didn't take the photo himself. So he surely stole from something else too.