I don’t know if this only happens when the daily limit is exhausted. But it happens all the time here for 2-3 months now. Also other people seem to have the same problem:
Maybe it would be a good idea to provide the Maxmind files from a local directory? I download this anyway for other uses, so it is already there.
And maybe it would be even better to provide the Maxmind files in a shared directory into the Discourse container to always have the up-to-date version? As I said I download it anyway and update the files once a day.