Safari on iPhone forgets website logins
I have online accounts with two news organisations, which I access using Safari synced between an iMac, an iPad and two iPhones (11 and 13). Latest OS on all of them.
On the iMac, after logging into both accounts initially, I've never had to do so again.
On the iPhones, both logins soon get forgotten and I have to log in as though for the first time. The login may last a few hours or even a day or more, but it's variable and unpredictable.
This happens only when using Safari – Firefox on the iPhones remembers my logins indefinitely.
Things I have already tried, unsuccessfully:
* Turn off adblocker (Crystal)
* Clear website data
* Turn off 'Prevent cross-site tracking'