I was angry earlier because my phone system removed the GMS (Google Mobile Service).

"Phone system" isn't really a term that's used. Perhaps "phone operating system" (but that's a bit long and technical) or "because [the phone company] removed the GMS from my phone."

Then I claimed in a previous diary that I wasn't going to buy any more Chinese -brand phones.

"Then" doesn't make sense because it refers to something that happens later, but you're talking about a previous diary.

"phones from Chinese brands" might be more natural.

But that's going to hit me in the face.

"Come back to bite me" might be the idiom you're looking for?

I did started paying attention to phone brands recently.

Your sentence is grammatically correct, but the "did" emphasizes a contrast, meaning that it would come naturally if the reader thought that you previously were not looking at phone brands. But since you don't really introduce that idea earlier, I would recommend just doing this.

China seems to sell very few foreign -branded phones, except for the most well known brands like Samsung and Apple.

I'm not considering Apple for now because of Apple's closed -source system and the huge difference between Chinese and international apps in the store.

Yesterday I saw the ranking of worldwide smartphone shipments in the second quarter of this year: Samsung, Xiaomi, Apple, Oppo and Vivo.

"Ranking" has an order, so there's a bit of ambiguity here as to what the list that you provide means. (But it isn't grammatically wrong.)

This ranking verifies my judgment: three of the five are Chinese brands.

The colon implies that your judgement was that three of the five would be Chinese brands, which also isn't an idea you set up earlier. I would suggest clarifying what your initial thought was first here, and then talking about the three brands.

Because of the Sino-US dispute, Huawei's does not have many international shipments are not many.

"Sino" is used more for historical disputes. Nowadays, most people would just refer to it as a U.S.-China dispute.

It seems my next phone may still be a Chinese brand, but I will change the OS to an international version, just like the one I am using now, in order to use GMS.