I have a Galaxy Tab S8.
Although the tablet isn't advertised as supporting HDR, streaming apps do seem to play in HDR on the tablet. For example, YouTube HDR videos have the HDR indicator in the quality settings for the video. This indicator isn't present on devices that don't have HDR (or devices on which HDR has been disabled).
I'm finding HDR to be problematic on the tablet. Dark scene HDR content I'm viewing in Amazon Prime Video app is too dark and loses significant shadow detail (when compared to same content in SDR). This is reminiscent of the problems you get if you play HDR on a cheap HDR TV. On such TVs the issue can be fixed by turning off HDR, forcing streaming apps revert to SDR.
Is there a way to disable HDR on the Tab S8?