Signature verification failed

I have VLC repository Index of /pub/vlc/SuSE/Tumbleweed/

Today I ran the command

zypper ref

and got this error message:

Signature verification failed for file ‘repomd.xml’ from repository ‘vlc’.

Note: Signing data enables the recipient to verify that no modifications occurred after the data
were signed. Accepting data with no, wrong or unknown signature can lead to a corrupted system
and in extreme cases even to a system compromise.
Note: File 'repomd.xml' is the repositories master index file. It ensures the integrity of the
whole repo.
Warning: This file was modified after it has been signed. This may have been a malicious change,
so it might not be trustworthy anymore! You should not continue unless you know it's safe.

Signature verification failed for file ‘repomd.xml’ from repository ‘vlc’. Continue? [yes/no] (no):

I have never received such a message before.

AFAIU VLC adds new repos for a Leap 15.1 and 15.2, and updates repo’s key.
Try to update repositories using theirs settings in YaST or anoter way.