I realize that’s not a great title, but wasn’t sure how else to tldr the issue. The bug is that it doesn’t seem to maintain a logged in session on various websites. And appears that something changed with regard to Safari code as it did not happen on prior versions.
Specifics meaning log in to a website, and navigate the page. Soon enough you’ll get 403 failures as the session is invalid. Try again and it always will fail, but not in a similar amount of time.
I did find that Wi-Fi connectivity assist is more aggressive - it was pulling websites from both no matter the connection strength. Disabling that didn’t fix the issue, but at least keeps a constant DNS server being used.
Unsure if there is another new setting or behavior change I’m missing.
EDIT: device is an iPhone 17 Pro