There was a network issue in the data centers infrastructure used by Masto.host and it caused about 15 minutes of downtime at 13:25 GMT. Everything is back to normal but any issues, please let me know. Sorry for the trouble this might have caused.
Mastodon v4.3.0 introduced a bug for anyone using OpenStack Swift that caused 'Media cache content retention' to fail if it attempted to delete a media file that did not exist (this is an edge case but it happens). I have created a patch and will apply it now on Masto.host. This will cause about 15 seconds of downtime.