What I find odd in these situations, that have happened multiple times now, is the companies go straight from "weak" licenses like the MPL, straight to "source available" ones. Surely it would have been a good idea to try a strong copyleft licence like AGPL first.
“You could ask or pay for an alternate licence” or “you’re almost certainly not using this in a way that means you need to open source your entire product” and any other rational argument you can think of are just met with “yeah but agpl” and that’s apparently just the end of it.
If it's to bait in companies to use your product and then offer more features under a proprietary license, then something that's more attractive to companies like a permissive (corporate charity) license is a better choice. If it's to ensure that everyone who uses the software can contribute to the development, something like the GPL or AGPL is better.
There can be other reasons to pick a corporate charity license, of course, but encouraging corporations to use your software is certainly one of the most common.
Developers are so entitled, they don't even ever reflect they are taking without giving back all the time.
It's a win/win/win, open source projects will still support it, so you don't get the backlash from the community, while those who just want to take will either pay or find a different project.
With BSL and similar, you end up looking like the "bad guy", and the forkers look like the "good guys". With AGPL you will still look like the open source "good guy", and if someone makes a fork they look like money grabbing assholes.
I assume there may be forks of the older code but I don’t actually know.