To play devil's advocate, perhaps he thinks he's being playful? Like, banter or something. At least, that's my experience when I have confronted ex-colleague about the same behaviours. Then again, those types are often very good at feigning ignorance 🤷‍♀️

On the other hand, it isn't funny if only he is laughing y'know. For something to be genuinely funny, the subject also has to find it funny. Otherwise it's bullying.