Os it normal for automatic high beam function to just shut down on it's own?

What is your question?

Automatic high beam function sporadically just shuts off (as if the switch had been clicked to off). This is beyond normal functioning (high beams on/off) of this system. Automatic indicator goes off, high beams and high beam icon go off, and have no high beams. After a few miles normal operation resumes. Dealer and Toyota deny that this is a problem.

What makes this problem better or worse?

Nothing has any effect

How long has your 2018 Toyota Highlander had this problem?

Since cehicle was new (2+ years)