Same situation. Redmi Note 7 pro and Mi-router 3 (firmware Padavan).
My 5 Ghz wifi is not available unless the ruter is set to China region code only (channels 149, 153, 157, 161, 165). With 10.3.5.0.EU stable there was no issue with my router set to Europe region code (channels 36, 40, 46, 48)...