When Elon bought Twitter he changed the verification system which used to be for public personalities to be trusted into a paid tier. So suddenly you could have a blue check mark by your name just like Rhianna, AOC, or any of your other favorite celebs for $10/month. Tumblr responded by selling rainbow checkmarks to anyone for $2.50 and so a lot of people sarcastically bought and gifted them to other people to make fun of Twitter. Ultimately they're meaningless