Phx-update="ignore" prevents `phx-no-feedback` from working

I noticed that if I add phx-update="ignore" to a form field like an input, this will not only stop its value from changing, but it will also prevent phx-no-feedback from being added to the element classes.

From the docs, it says that attributes can still be updated:

The “ignore” behaviour is frequently used when you need to integrate with another JS library. Note only the element contents are ignored, its attributes can still be updated.

Is that behavior expected? And if so, how should someone prevent form errors from showing up in an element that has phx-update="ignore" before it was first changed (since it doesn’t have the phx-no-feedback class, it will show an error on it even if I’m changing other field)?