Unity is a tool that game developers use to build games. You don’t have to use Unity, but lots of really popular games use it and it makes development easier. Recently, the company behind Unity (also called Unity) decided to add an extra fee for using Unity. That would have been bad enough, but Unity went with adding a fee in which the game developers need to pay every single time a customer installs their game.
This was a startlingly bad idea, because you end up punishing games that sell well. But it also opens up entire cans of worms, because trolls could easily mess with developers by simply buying a game, then installing, uninstalling, then reinstalling again and again. And because the fee is applied per install, a single troll could easily build up massive fees for the developers. On top of that, this new fee is applied retroactively to all games that were built with Unity. So it doesn’t matter if you built your game 10 years ago - you’ll still get charged if a user installs your game.
In response, many developers are pushing to boycott Unity, with many saying that they would go bankrupt with the new fees. It also came to light that many of the top executives at Unity sold a large number of their shares in the company shortly before making the announcement of the new fee, showing that the top executives knew that the fee would be unpopular but went with it anyways. It also brought up the concern that they were engaging in insider trading, which is illegal.