Most every OTA channel here in Spain (at least in Valencia) is 1080i, with a few being 720i, but there's two 4K test channels, one SDR and one HDR. Not sure of the bitrate, but the SDR one looks stunning on my TV (which "supports" HDR but looks horrible in HDR mode). They usually just play loops of B roll of various Spanish things, festivals, random clips of theatre productions and things like that. It's pretty neat!