Again some bored blogger had nothing to do and went with h this clickbait-ish headline!

The reason for the stat showing but also misleading millionaire numbers going up is pretty simple, there were around point around ~36000 addresses with a balance between 50BTC + a few satoshi, most of them being from old blocks that have been mined and never moved.
Once bitcoin passed back over 20k, those addresses become richer than 1 million, but it's highly probable that there aren't 30 000 new millionaires but more like in the thousand if not hundred since a ton of those coins are most likely lost, and quite a few should belong to the same individual, Satoshi!