Strobe effect with HDR on Apple TV

Since the update to tvOS 12.3, I’ve seen a consistent “strobe” effect when watching HDR content on my Apple TV 4K. I’ve seen a few older posts describing this, but there didn’t seem to be a solution, so I’m posting a new question. It’s a sometimes subtle, sometimes not so subtle flickering of the darkest parts of the image, and I’ve tried everything I can do to fix it: I set the ATV to different frame rates, toggled match content settings, set chroma to 4:2:0, used different HDMI cables (including a new one purchased today), nothing makes a difference. I thought I would try downgrading the software to 12.2 but apparently that’s not an option on the 4K...

I’m using a TCL Roku TV and I’ve tried the same content directly through the apps on the TV, and everything looks fine. The only thing I can assume at this point is that it could be a hardware issue with the ATV, but the problem only started with the 12.3 update for me. I would just bypass the ATV, but some of my HDR movies (in this case, Harry Potter) are only in HDR on the Apple TV and not anywhere else (Vudu, Movies Anywhere, etc). Does anyone have any thoughts or suggestions?