Some functions of Eye of the Flügel do not work

Even if I have the Eye of the Flügel, I cannot continue to fly after the flight gauge is empty.
Is this a specification? Or is the book out of date?

1.20.1
forge47.2.20
Language Japanese
Other mods are only available for JEI

It's a known issue with a fix in the pipeline.

Ok thanks.
I see it's an unintended spec.
Good luck with the fix.