Since the most recent iPhone IOS update (18.5) a website that is only http and that I visit several times a day now requires me to re-enter my username and password at least the first time I visit every day. It did not used to behave like that, and it is not happening on my iPad.
iPhone 16e, iOS 18
One practical thing you could try is adding the site manually in Settings > Passwords, so Safari can still auto‑fill your login even if the session clears. Not a perfect fix, but it often makes things less frustrating.
Interesting; I went to add the password as you suggested, and it told me there was already a password for the site. Not only that, but when I went to the site it didn't bother asking for a password. A weird glitch in the Matrix. Thank you for your suggestion.
Safari forcing website to log in with username and password.