Really, this is an incredible own goal on Google's part. Although I won't resist the opportunity to rag on them, I also grudgingly admit that this is probably incompetence rather than malice and likely yet another instance of something falling through the cracks in Google's all-powerful, rarely examined automatic algorithms (though there is circumstantial evidence to the contrary). Having a human examine these choices costs money in engineering time, and frankly when the automated systems are misjudging something that will probably cost Google's ad business money as well, there's just no incentive to do anything about it. But it's a bad look, especially with how two-faced the policy on Manifest V3 has turned out to be and its effect on ad-blocker options for Chrome.
UPDATE: I hate always being right. Peter Kasting, a big wheel and original member of the Chrome team, escalated the issue and the extension is back, but for how long? And will it happen again? And what if you're not a squeaky enough wheel to gain enough attention to your plight?
It is important to note that this block is for Chrome rather than Chromium-based browsers (like Edge, Opera, Brave, etc.). That said, Chrome is clearly the one-ton gorilla, and Google doesn't like you sideloading extensions either. While Mozilla reviews extensions too, and there have been controversial rejections on their part, speaking as an add-on author of over a decade there is at least a human on the other end even if once in a while the human is a butthead. (A volunteer butthead, to be sure, but still a butthead.) So far I think they've reached a reasonable compromise between safety and user choice even if sometimes the efforts don't scale. On the other hand, Google clearly hasn't by any metric.
You may have suspected by the relative lack of activity on this blog and at Github that there aren't going to be any new features in the next TenFourFox release, and you'd be right. Between my wife and I actually being in the same hemisphere for a couple weeks, an incredible amount of work at the dayjob and work on the POWER9 side for mainline Firefox I've just been too short-handed to do much development this cycle. It will instead be numbered FPR16 SPR1 with security patches only and I'll use the opportunity to change our upstream certificate source to 68ESR. Watch for it sometime next week.