for Chinese devices, there's no way to disable them.
the difference is, for Windows, having Bing on start was a feature (although a bad one). for Chinese devices, you just get ads - you're stuck with ads while changing your brightness.
And as other commenters have pointed out, lots of budget phones and hardware jam ads all over the place.
Premium hardware too (hello Smart TVs)
Uh can you stop spreading misinformation? Try google "disable xiaomi ads" it takes you like 5 minutes to make all ads gone on MIUI or HyperOS. Sure the opt-out buttons were hidden deep behind menus for maximizing profit.
But be warned, in certain countries you are getting a modified ROM from your local re-seller, in that case some ads can't be disabled and they are not from Xiaomi. The only solution is to flash your ROM to the official releases.