Earlier quoted context omitted.
>Mozilla’s first integration of Pocket was poorly done, and rightfully raised complaints. But since they have purchased it, a lot of those complaints have been resolved. Off-topic, but I find current integration equally poor. Why do I have to spend extra clicks to login every time I want to add something to Pocket? Why it doesn't use stored credentials just like Sync does?
> If you sign into Pocket with your Firefox Sync account, this is the behavior. It should only prompt you to re-login if you've cleared cookies. Even then, you can re-login via FF Sync without entering the password in again. If you're logging in with a service other than FF Sync (ex: Google), I'm not sure how you expect FF to know what your credentials are to log you in.
Looks like Cookie AutoDelete extension somehow affects Pocket but not Sync. Thank you for hint!