Some clients using the PROPFIND method in their WebDAV implementation are no more able to connect.
Such clients are Windows native explorer or Enpass (https://enpass.io).
This can be reproduced with a curl call and an empty PROPFIND payload.
curl -v --http1.1 -X PROPFIND -u myuser https://tuleap.example.com/plugins/webdav
Looking at code, this is due to the getQuotaInfo method of the Directory class of the SabreDav library. This method requests a realpath on a not set $path attribute. But since PHP 8.0 this is no more supported and triggers an exception. Such code is called when related properties are requested by the PROPFIND payload (empty payload means all properties).