Xiaomi is the essence of Chinaware: Xiaomi are hard to open/repair (environmental unfriendly), workers don't get a fair wage, materials are not fairly resourced, it has a locked bootloader, they have their own bloatware (MIUI), probably contain spyware, and likely don't even pay fair taxes.
Also, the successor of Fairphone 4, Fairphone 5, has 5G and OLED.