Login as guest with store-api

When I do the user registration via the store-api as a guest:

https://my-url.com/store-api/account/register

I cannot login via

https://my-url.com/store-api/account/login

with following error message:
image

When I do exactly the same, but not as a guest, it works. That means I register with the same body data besides „guest“: true (which I deleted in the body).

Any suggestions what might be wrong, when registering as a guest.

I use shopware 6.4.13.

Were you able to find out how to login as guest?

No unfortunately not.