If you login to the PayPal account you received the email too, you may notice more messages in your account:
Temporarily unable to load page. This may be due to temporary issues with our servers, or you may have been disconnected from the Internet. If you're connected to the Internet, try reloading the page at a later time. We apologize for the inconvenience.
Or if you try to remove any of your banks and cards:
We can't remove this card right now Looks like something went wrong. Try again later.
Suggest to contact PayPal support while logged into your account and change your password. PayPal is likely having issues on their end. There is also a Reddit thread about this.