@_az Yep, I came back to post this and found you'd already posted it, with an excellent citation. Thanks!
I can confirm that many certificates have been issued recently under
online-server.cloud. They just don't necessary show up in that particular crt.sh search.
Regarding the Public Suffix List: I have been trying not to encourage folks to get added to the PSL lately. The PSL gets distributed to all browsers, and making it bigger is a burden to the whole web. Yes, services that hand out subdomains to anyone fit the technical definition of what should be on the list, but there are so many services that meet those criteria that if they were all added to the PSL it would be way too big. The web needs a better solution but so far no one has been able to come up with one (other than eliminating cookie setting on parent domains). The upshot is: when sites get added for the purpose of changing how Let's Encrypt apportions rate limits, that's a burden on a shared resource.
We have also dramatically increased our rate limits in recent years (50 per registered domain per week) and have streamlined our process for handling rate limit increase requests, which hopefully reduces the incentives to get added to the PSL.