As for GitLab, it isn't changing to BSL, so they can keep using it.
Think of a few what?
You listed a bunch of links to GitLab CE, which is not their enterprise offering, does not compete with their enterprise offering, and has an order of magnitude less functionality and no support. Again, their enterprise offering is already under a proprietary license.
GitLab openly supports anyone deploying and managing GitLab CE: https://hub.docker.com/r/gitlab/gitlab-ce
Not sure what you're alluding to?
But I don't think either not-fully-free-but-related-to-open-source model is as disappointing as the rug-pull of a license change itself.
Aside: I think BuSL can be a great license for software that's not part of any customer/user's way of earning a living. Id Software basically used to informally use a similar scheme for all their game engines (and maybe still do?), where the engines get released as F/OSS some number of years after the game comes out, and that has ended up enabling the development of lots of good open-source games and game engines.
It can basically undo the damage caused by our insanely long default copyright terms. Not the same thing as providing open-source code up front, but still a very pro-social thing to do.