The answer is no. There was a Cloudflare article on ECH a while back that mentioned the fallibility of using reverse DNS, but I am having trouble locating it. In any event, the people working on ECH have coined a term called the "anonymity set". Below is a Cloudflare article that uses this term.
The "anonymity set" refers to the number of possible domains using a single IP address. The existence of that term implies that some IP addresses must have a number of domains associated with them, greater than 1. With these IP addresses, one cannot determine the domain name, the one that the www user sent, from a PTR query alone. Even prior to the introduction of SNI to TLS, when the only way to offer HTTPS was by using a dedicated IP address, discovering the contents of the encrypted Host header via reverse DNS was neither easy nor reliable.
If there are still people reading HN who believe that reverse DNS is reliable and makes plaintext SNI and ECH moot, and are going to comment as such in the future, I would be happy to post the results of an experiment where I take the DNS data for all the domains currently submitted to HN, i.e., a list of IP addresses found in the A records for these names, and do a PTR on each one. We can look at whether "most domains" are identifiable through PTR records.
Also remember the question is not whether ECH protects 100% from someone discovering what domain name the user sent. It does not. The question is whether ECH makes it more difficult to discover than simply sniffing plaintext SNI on the wire, which, of course, is even easier and more reliable than reverse DNS.
I will bet 10$ that with reverse DNS + DPI to try to suss out page size and caching behaviour you can identify anyone accessing this website and downloading the 7TB database.
No one has to "access this website" because they can read its contents in Internet Archive, Common Crawl, Google Cache, etc. Page size and caching behaviour will not work if the person is using HTTP/1.1 pipelining to request multiple pages from a variety of websites from Internet Archive, over a single TCP connection. (Using CDX API not HTML form at Wayback Machine page.)
The 7TB is via torrent, not via HTTPS. No rDNS needed.