Nail on the head, this is new. When someone can steal your release date then why bother making a game? Make a game, release a demo, demo is stolen and published the same week, 6 months before the dev was ready to release.

Demos are (up until this week) the #1 for studios to do marketing.

Marketing will change now, to more socials being required (YT etc), and even then only small bits here and there as decomp will happen from video as well.

The marketplaces that adapt to this and enable devs will help, hopefully.