I use Celcom 5G on my iPhone 14 Pro Max and Samsung A13 5G. Umobile 5G on my iPad mini 6.

So far, I have no issue with connectivity and the speed is marvellous at my home in Kota Damansara, can get around 500Mbps to 850Mbps max.
Even in my bedroom and the dining area the signal coverage was like 3 to 4 line (full bar). Maybe my place is okay for 5G speed & coverage (outdoor & indoor).

Tried using 5G also at my hometown in Ipoh, near Sunway City Tambun. Surprisingly I got excellent Gigabit speed with full bar 5G at my house.
I am considered lucky, perhaps.