Can't view registry tags (500 Internal Server Error) / How to purge complete docker registry

Internal Server Error when accessing Registry via API/GUI

Dear Gitlab Community, I can’t manage my gitlab registry nor tags.
The userinterface is just grayed out.

The according request fails with error 500:
curl 'https://gitlab.*******/api/graphql' --data-raw $'[{"operationName":"getContainerRepositoriesDetails",

general information

I’m using gitlab selfhosted as docker container.
I upgraded from 13.9.3 to 13.11.3 - both versions show this behavior.

Troubleshooting

I tried to fix the likely broken registry by removing broken data the proper way.

garbage collection

gitlab-ctl registry-garbage-collect -m did not remove any images. In the output I see images/tags/?? from the registry which gives me the error.

removing tags/images/repository by hand

I also tried deleting the tag

curl --request DELETE --header "PRIVATE-TOKEN: **************" "https://gitlab.***/api/v4/projects/51/registry/repositories/16/tags/latest"
      % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                     Dload  Upload   Total   Spent    Left  Speed
    100    39  100    39    0     0    204      0 --:--:-- --:--:-- --:--:--   205{"message":"500 Internal Server Error"}

I also tried deleting the whole repo

curl --request DELETE --header "PRIVATE-TOKEN: **************" 
    "https://gitlab.*********/api/v4/projects/51/registry/repositories/16"
      % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                     Dload  Upload   Total   Spent    Left  Speed
    100     3  100     3    0     0     15      0 --:--:-- --:--:-- --:--:--    15202

both request don’t do anything

Question: Purge all and start new

since in at least 2 other projects I get the 500 when just visiting the GUI onhttps://gitlab.****/group/project/container_registry I’d like to start new. So the question is how to purge all registry data an setup a new? Or is there another solution?