You may actually be seeing a TV issue or TV setting that's making the judder... TVs usually have their own video enhancement functions, like noise reduction, motion compensation features, etc that are on by default. Trick is, your ATV4K has all the same stuff and a (probably) better chip. The TV's video enhancement algorithms may choke on the ATV4K's output that's already been enhanced.
My suggestion is that you try turning OFF all such video enhancement features on the TV, then reset your ATV4K's video settings. The ATV4K will attempt to sniff the TV's capabilities and choose a default video mode of the highest res and frequency that your TV can support. From there, you can enable HDR on the ATV4K, try for a superior gamma setting, etc. If the 'judder' continues, you might try a different default setting like 4K HDR (30fps).
On my setup, my ATV4K usually looks great on my lower-end LG 4K HDR TV with Match Content turned off. The only gripe I've noticed is that HDR mode occassionally looks too dark on night scenes in 4K content encoded with DolbyVision; (my TV doesn't support DolbyVision). In these cases, if I switch the ATV4K to send 4K SDR to the TV, I can comfortably see more detail in the darker scenes. I suspect my TV just doesn't have the brightness expected from an HDR10-capable TV (but perhaps I'm nit picking :-).