That's been happening for me as well. I always get a prompt to sign in if I try to pull up the website on its own, but if I use a previous link such as one from an email I do not have to sign in. I never want to sign in because I don't know my password but I can sign in on my phone with my fingerprint. I just now found an old email and hit the link to see shops and I saw that there are actually no shops available, as there had been before this started happening. I think it might happen when there are no shops.