Pick the production before the resolution
The year, synopsis and film format tell you what you are choosing. A sharp poster does not describe the resolution of the video supplied by another application.
Full HD can be the comfortable choice
1080p is useful when the viewing offer and display support it. Judge the picture during normal movement, not only a paused close-up, and favour steady playback over repeated quality changes.
A 4K label needs a supported path
Check the title edition, service plan, device and display. A 4K television does not turn every stream into native 4K, and resolution alone does not promise HDR or a particular audio format.
When quality drops
The player may be adapting to the available connection. Compare another title in that same application, then another service, before blaming every TeaTV catalogue page. Its filters cannot repair a remote video source.