Hello everyone, thank you for the reports.
The VT in question is only a part of the Greenbone Security Feed, but missing from the Greenbone Community Feed. However, the new policy XML files in the Community Feed still reference it. I have opened an internal issue to get this sorted out!
Note that we have also improved our backend recently to make it more resilient in cases like these: https://github.com/greenbone/gvmd/pull/1366
With this PR I am not able to reproduce the error, please check it out.