Your address and phone point to a location, not necessarily a valid identity but I understand you may be hesitant to share personal info with just anyone. If you are a EU citizen you can ask them exactly how long your data is retained and who may have access to it (it’s actually published to on their website). They use it only as a 2nd level verification to prevent spam (not shared with 3rd parties). As a German/EU company, Hetzner is subject to all regulatory requirements for handling of personal information and so when leaving, you can also request the deletion of your data (or just consult their retention period)