Can’t find the grammar error in the the sentence

Solution 1:

There are 2 things to be noted in the above mentioned sentence:

1. The word 'quite' must be used insted of 'quiet'.

Quite means to a certain or fairly significant extent or degree; fairly.

Quiet means making little or no noise.

2. There's no need of using a comma before 'because' as it's preceding a dependent clause. For more information see this link in regard to comma usage before the word 'because'. But using comma doesn't make the sentence grammatically incorrect, it's just unnecessary.

Therefore, we conclude that the more grammatically well structures sentence is:

I find Chinese English quite funny because they don’t use proper English grammar. [Correct]