The DMA designated gatekeepers seems to be pretty well-targeted as a real law that's currently on the books.

It applies solely to Alphabet, Amazon, Apple, ByteDance, Meta and Microsoft.

Going by that list, YouTube and GitHub would be impacted. They have social features and primarily host user-generated content.

Imagining that these laws will be precisely written to avoid any services you like is a dangerous fallacy. That's how people rationalize bad laws.

Remember when all of the surveillance laws were only going to target the terrorists? Look how far that drifted.