Hello Samsung developers,
here is a report on github 10bit H264 with hardware decoder black video image · Issue #371 · mpv-android/mpv-android · GitHub
and there a user and a video player developer tested that on Samsung devices with Mali V52, Mali-V76 and Mali-V77 video processors and later supports H.264 10-bit.
The problem is that you have not implented H.264 10-bit hwdec via MediaCodec for your Exynos processors. More details see in github report.
Please fix it in next Android 11 update.