INAL, but from my understanding that's exactly what GDPR itself suggests to do:
> The controller should use all reasonable measures to verify the identity of a data subject who requests access, in particular in the context of online services and online identifiers.
Thats mainly because [2]:
> There is a very real concern of fraudulent requests from bad actors, who might use a customer’s data for nefarious purposes.
While it's great to know that noone else is able to delete my account, it still feels shady af.
[1] https://eur-lex.europa.eu/eli/reg/2016/679/oj#d1e1374-1-1
[2] https://konfirmi.com/blog/gdpr-personal-data-id-verification...