Set max_resolution_tier on Mux assets deliberately; 1080p is the default and 4K needs 2160p. Match the tier to real playback needs so you are not paying to encode pixels nobody watches.

Context: Official Mux docs (4K streaming): documents the resolution control agents leave at default. max_resolution_tier caps the encoded resolution and defaults to 1080p; raise it to 2160p for 4K output. It also matters for cost: higher tiers encode more pixels, so set the cap to match what your audience can actually play. Per-asset settings can still go lower than the global default.