Yea, 50" go up a few days ago, I still catch for RM2199.
Seems seller smelling good and fast profit.

Reviews done earlier has been probably with V2xx firmware and slow and sluggish UI.
Now is in V3xx range and much better.

12.12 Sony 49" X75H will be RM2399 (but no Dolby Vision/Atmos,HDR10+)

Seems you didn't read my previous posts. 
I have been one step from buying Hisense 50A7400F,
but give up seeing bleeding in they screens from many users.
Most real detailed spec you can found:
https://www.displayspecifications.com/en/model/be9e1ef9

Of course Sony and Samsung is better, but didn't match my criteria for allocated budget (~RM2K ,up to 50").
Samsung 50TU8500 no Android, no Dolby Vision (330 nits same)
Sony 49X75H no Dolby Vision/HDR10+ (340 nits)
Sony 49X80H IPS panel, no HDR10+,over budget (500 nits)

I don't want to repeat same thing again, but as you ask about black contrast,bellows are same pic I made today
(in a dark room).

Black screen test


White screen test


Calibration test


Dimming test


HDR10 YouTube




After 18 days of testing.....(and watching) TV has 10 day+++ running time...

As stated earlier...version with older firmware V2xx and early V3xx, yes a bit.
I got TV with V356 and no sluggish.
Tried many version V378,V379,V395 and end up with V606 (experimental).
Many versions are on the net ,just download and try.Have 2 basic ,one is IMG and other is OTA.
IMG version flash everything (good if you brick TV !) and OTA which keep your apps and setting.
Can flash up and down.
UI is fast and have no problem.This month TCL supose to upgrade to Android 10.

This is my UI screen..