Thanks for this info, stevieb. You and pfaut have given me the confidence to proceed with Valkey and in the week or so I've been testing it out it has worked really well. My Perl code is accessing it via CHI::Driver::Redis::SortedSet and it has been very easy to drop into some of our existing CHI-driven code in place of (or as l1_cache addition to) some of our other less efficient back ends.

Just out of curiousity, what was the reason for your initial Memcached to Redis migration? Aside from the non-volatility of the Redis store there doesn't immediately seem to be a massive difference between them.

Regardless if the fiasco is fixed, we're sticking with Valkey.

Sounds very prudent. I suspect we will do the same.