I see those messages, too. I spent some time trying to understand the problem, but I didn’t come to a definitive answer.
What I saw is that my rspamd communicates with 88.99.142.95 but it logs the timeout.
I think that the message is harmless.
Everything is as described in this open issue:
the fuzzy database is a remote spam database that locally you sync from time to time on your server, you missed a sync probably because the fuzzy.rspamd.com was down, overhead…