[Sesshoumaru]

Figured it out.  To Fix:
1) Navigate to \Users\%userprofile%\AppData\Roaming\Kodi\addons\metadata.common.anidb.net
2) Find the XML-Tag for "ParseTVDBArtwork"
3) Replace "<RegExp conditional="Fanarts"" section with

xml:
      <RegExp conditional="Fanarts" input="$$6" output="\1" dest="16+">

        <RegExp input="$$5" output="&lt;thumb dim=&quot;\2&quot; preview=&quot;http://thetvdb.com/banners/_cache/\1&quot;&gt;http://thetvdb.com/banners/\1&lt;/thumb&gt;" dest="6">

          <expression clear="yes" repeat="yes">(?i)&lt;BannerPath&gt;([^&lt;]*)&lt;/BannerPath&gt;[^&lt;]*&lt;BannerType&gt;fanart&lt;/BannerType&gt;[^&lt;]*&lt;BannerType2&gt;([^&lt;]*)&lt;/BannerType2&gt;</expression>

        </RegExp>

        <expression noclean="1">(.+)</expression>

      </RegExp> 

Please note that I removed the reg-ex part about matching the fanart colors. It was not able to handle empty colors - didn't match them. It seems that TVDB does not fill that tag anymore and thus all the regular expressions failed. I know its quick and dirty, but now it works for me again.

Please be aware that you also need the above mentioned fix for the "extended local headers" in ZIP files. I have cloned the Leia git branch and merged the change locally. For new stuff, since about November 2019, you definitly need it as the provided en.zip  files are formatted like this. Hope this info helps.