Yes, LE upgraded the unbound system it uses for that to version 1.18 (and then 1.19) after long using v1.16.
This has caused some DNS Challenge failures with more than around 20-22 TXT records. Which looks like you are just over that limit.
Use the https://unboundtest.com to check your TXT record with these diff versions.
LE has not yet provided an official response of their plans. See below thread for others like this.