I've had similar issues before due to inadequate hardware, and maybe that's what it is again.
I have in my lap two different generation Fire Tablet 10"s. One Gen 11 (2021), one Gen 13 (2023). The Gen 11 displays video and audio from an ATSC 3.0 channel. The Gen 13 only audio. I had this same problem with a Gen 9 tablet, and my memory is that it was an issue with bit depth, but from where I'm sitting, I can't see a difference in the specs from gen 11 to gen 13.
I've submitted diagnostics from both devices after playing a little while. Can you tell me what's up?
Thanks!