With this change, release notes for buster (and former releases) won't be built regularly (their last build (e.g. from last night for buster) will remain online). I see that buster is LTS until June 2024, but last commit for its release notes is from 11 months ago. So I think that the current status is ok.
In any case, if anybody commits updates to the release notes of buster and needs
them to be rebuilt once again (to show these updates in the Debian website), please ping us at email@example.com or submit a MR to the cron repo (in a similar way of the change above).