https://tftcentral.co.uk/articles/pulse_width_modulation

Our eyes, and hence the rest of our bodies, are sensitive to things that our thinking brain doesn't really directly notice.

Some measurements of various devices from NotebookCheck.net - https://www.notebookcheck.net/PWM-Ranking-Notebooks-Smartphones-and-Tablets-with-PWM.163979.0.html

Glad you got it figured out!

Hang in there!

Best wishes,
Scott.