all miui 10 have abr 4, only old version of miui 9 have arb 3, i also own this device, so i know what im talking about, latest oreo for fatboot https://bigota.d.miui.com/V10.3.1.0.OEIMIXM/whyred_global_images_V10.3.1.0.OEIMIXM_20190426.0000.00_8.1_global_8fe177760d.tgz, also you can try this [UNOFFICIAL BUILD] A Pi/e/ test ROM for the Xiaomi Redmi Note 5 Pro "whyred" but better flash oreo than insyall official /e/ so you can get otas