Something else that I only found out from comments on another thread about this is that once you start the 24 hour timer, you have to allow unverified apps within one hour after the timer stops. If you miss this one hour window you have to wait a full 24 hours again. And it will not give a notification when the 24 hours is up, you need to set your own alarm.

EDIT: found the thread where others are talking about having to wait an additional 24 hours after missing the one hour window https://lemmy.world/post/51966349/25850937

To clarify - the one hour window is how much time you have to turn on the setting after waiting the 24 hour timer. As in, you have one hour to push this button. If you miss this window to turn the setting on, you have to request to turn it on again and it resets the 24 hour timer.

Once you turn the setting on you can select the option to turn it on forever.