If this happen in SDR ,  disable local dimming , set it to off .
If this happen in HDR , there is nothing much you can do except to turn off the subtitles .
Sony's  LCD TVs don't handle subtitles very well , unlike the Samsung LCD but they come with a cost of crushing smaller highlights .
There is no perfect solution on LED LCD TV currently .

Actually if u listen closely to the review, it wasn't a very good review on the x900h from hdtvtest nor is a detailed one. His review unit is a 75 inch model. He is saying it's a value pick for a 75 inch model because nothing else at that price point have that features in the UK. It's very specific to that size the review. At smaller sizes, the choices becomes more and competing offering is also more compelling. He actually like the x950h more. The review is much more detail and like twice longer the video length. Unfortunately this is not available in Malaysia.

X900H has garnered a lot of compliment due to having HDMI 2.1 ports , native 120hz and 10 bit color panel and a FALD system , all in one packages with such a great price .

But if we are talking about pure PQ performance , it is not meant to compete with OLEDs as those belongs to the premium market .
X900H comes with a lot of sacrifices , such as only having 32 LED dimming zones limited its FALD performance by quite a bit .
The cost of having very low gaming input latency is evident , as Sony has limited post picture processing on this TV .

Basically X900H is what X850 from previous years are , but with a local dimming system and HDMI 2.1 ports .
If we are looking for the best LCD this year , it would be Samsung's Q95T no doubt . But it is far more expensive than other brands .

What is the best price for 75" 9000H?

This is SenHeng in taipan usj, not sure about other senheng.

Worth to get this 65 inch over x80h 55inch or x90h?