Can't login anymore via Apple ID

I have an active etoro account connected with my AppleID (So I usually login using my AppleID). For some reason, I can't login anymore (I was travelling for three days within Europe and I saw this message for the first time in another country).

When I try to login, I don't see the usual screen but a blank screen with the text (translated from German):

For security reasons, you must choose a new password. An email with instructions has been sent to your registered email address.

However, I don't receive any email. Usually, the forward from Etoro to my personal email adress works. It is also activated and there's nothing in the spam folder.

Since I can't login, it's not possible to contact the support of etoro via proper channels. I'm afraid the instructions sent from etoro to my "hidemyemail" Apple email don't arrive since it might come from another domain / subdomain that is not whitelisted. I haven't received anything at all.

Does anyone have an idea?