according to jawn aka. 1WTC from the discord,
"Please note, DMU Beta 1.12 will be going offline in a few days time whilst we start the transition to DMU 1.16. DMU Public 1.12 will still remain online.
If you have any builds you would like to save on DMU beta a backup will be made on our end and we also encourage you to use a world downloader to make backups of any of your builds you wish to keep.
DMU beta however will be returning with the launch of 1.16"