Your Tab S9 FE's screen has a resolution of 2560x1600 (Quad HD), not 3840x2160 (4K UHD). Therefore, it can only display videos at resolutions up to its native capability.
Exynos 1380 Processor:
The processor in the Tab S9 FE also supports a maximum display resolution of 1440p, which further limits 4K playback on the tablet itself.
How to confirm the resolution you're seeing
Play a 4K HDR video: on your YouTube app.
Tap the screen: to bring up the playback controls and tap the gear icon to open video settings.
Look at the quality settings: and see if "2160p" or "4K" is available. You will likely see a maximum of "1440p" or "2K".
What you can do
Adjust Your Expectations: Understand that your tablet's hardware has limitations.
Try QHD (1440p) HDR: You can still experience HDR and a high-quality viewing experience by selecting a 1440p or "auto" setting for 4K HDR videos on your device.
Use a 4K Display: To truly watch 4K HDR content, you would need a device or external display that supports 4K resolution.
We request you kindly share the log file. Also, share the video clips and images for better understanding. This will help us to investigate further and resolve this issue.
To share the log file: Open Samsung Members Application > Support> Tap on send feedback> Choose Composer> Select error report> Select the appropriate issue category> Type your query and send.
Note: To ensure relevant log information is included in the error report, submit the report within 3 minutes of encountering the bug or error, and do not terminate (swipe away) the Samsung Members application until you are notified that the report has been sent. This can take up to 5 minutes.
