I have a profile on AskUbuntu.com which is recognized on my StackEchange profile (https://askubuntu.com/users/780824/camion). I have already asked and answered questions there. But even though I'm logged in stack exchange, Askubuntu does not see me as logged in. I have a long history of problems with that and though I have been able to access it up to end 2018, and I don't understand why it can't do it anymore.
I have seen multiple questions about similar problems, but they all are older than 2018 and do not really helped me solve it. Amongst other, they proposed to log in with the same user and password, but using the same user and password on two different log in systems is a security hole. either your credential cookies are shared, or one should use different logging info.
EDIT: it has been suggested to deactivate third party cookies blocking, but I do not want to ruin my browser's tracking protection.