as we all know, it is clearly recommended to avoid any automatic picture processing stuff, including automatic backlight. In the latest "Matrix Resurrection" movie, the opening sequence shows a blinking cursor, this clearly helps to identify, if any automatic backlight adaption is changing your video. Have a look at the attached video, 10 seconds, and you'll notice the lamp-on-off-effect on my 2020 Samsung The Frame.
Unfortunately, the original "The Matrix" (1999) has a very similar opening sequence, but I could not reproduce the same effect. At least not from the DVD release.