Why is PyCharm ignoring unresolved reference errors?

Question

PyCharm

Good day to all. Such a problem: PyCharm does not highlight errors in unresolved reference code.
More precisely, it underlines them in a very strange way: first, for 1-2 seconds, it underlines all errors of this type, then for several minutes all underlines (namely, unresolved reference errors) disappear.
That is, it first underlines the view code

for 1-2 seconds (highlights the unresolved reference error, because it was necessary to first write 'from typing import List'), then it stops underlining for a few minutes, as if there were no errors (and so on cd). Who knows how to fix the error?