Stuttering type effect on playback on Apple TV app (Stemio Lite) -- is this a limitation of the app, the media or something else?

I'm getting stuttering on playback in the new Stremio Lite app on Apple TV using Real Debrid. It's not the traditional stutter like slow internet speeds, it's as if frames are lost in playback.

Is this a processing issue w/ the apple TV app, incompatibility with the high bit rate media (4K HDR, 4K DV) or something else?

To be clear i'm not blaming Stemio Lite necessarily, but it's making the 4K movies hard to watch due to this.

disclaimer: i'm brand new to Stremio and RD