Intensive Shadowsocks blocking in China since mid-September

There are reports of a sudden increase in the blocking of Shadowsocks servers accessed from China. It sounds like it begain, suddenly and noticeably, on September 16 or September 17. From what I can gather, servers are getting blocked (by IP address) within about 30 minutes of being connected to from China—but I don’t know if that’s consistent across all servers, only some of them, or what. I don’t really know any specifics.

There are some threads on Reddit /r/shadowsocks:

The shadowsocks-windows issue tracker also may have some discussion, but it’s mostly in Chinese and harder for me to judge.

Here’s a post about a SOCKS proxy service mentioning increased blocking:

Are any other protocols or circumvention systems being affected, besides Shadowsocks? I looked at the recent Tor metrics from China and I don’t see anything significant on September 16. But the number of users of obfs4, which is the pluggable transport most similar to Shadowsocks, was already close to 0, so it’s hard to say whether anything changed.

Here’s a thread from 2017 on a similar topic. And a report also from 2017 that Shadowsocks, Lantern, and Psiphon were affected in October of that year.