Need help with fixing delayed notifications on a China-exclusive phone from Xiaomi.

One of my classmates has just bought the Redmi Turbo 4 Pro at a local Xiaomi shop that also imports China-exclusive Xiaomi phones, and he's really happy with it, but there's just one problem: his notifications (Facebook, Zalo (instant messaging app in my country), etc.) are delayed by quite a lot. What should I do to resolve the problem?

edit: I think his Redmi is not unlocked, and I don't think my classmate has enough interest in unlocking the bootloader either.