This is Fully-Kiosk home page, and this is kiosk-mode repository. Your configuration is a configuration for kiosk-mode and it is not related in any way with Fully-Kiosk Browser.
You should be referring to [email protected] because the latest version of Fully Kiosk Browser is 1.60.1-play.
Now, if you are in [email protected] and you are using Home Assistant 2026.6.2 it will not work. You can find the reason if you read the release notes of [email protected].
After the kiosk mode update, everything is working properly again and I've lost the white sidebar.
And all that after a clear warning from Kiosk mode​.