Hi Graeme and Jianxia,
We are having an issue with this as well with our embedded AGOL content in an Experience Builder. Previous to the update this week, we didn't have any issues at all and didn't need to clear the cache on our browsers.
I realise clearing a cache is an easy temporary fix, but will there be a long term solution for this? For people who aren't very tech savvy, they assume the app isn't working and will stop using it. The end users who access our experience builder aren't always tech savvy, so we are receiving a lot of negative feedback from our app which was working just fine before the update!
Something that would help is if we could change the settings for our published Experience Builder to "always require login" when the app is opened, or to set the expiration of the token (i.e. "your session has timed out" after 1 hour). Then the authentication token would get carried through to the embedded AGOL content.