Learn Turkish: Troller kötü paylaşımlar yapıp duruyor.

This uses the continuous repetition structure you are currently learning: verb root + -(y)ıp + durmak. Here, we take yap- (to do/make), add the -ıp connector, and finish with the present continuous verb duruyor. Even though durmak usually means "to stop" or "to stand," combining it with another verb like this means the exact opposite: to keep doing something repeatedly (often to the point of annoyance!).

Why is the verb duruyor in the singular form when the subject (Troller) is plural?

In Turkish, if a plural subject already has a plural suffix (like the -ler in Troller), adding the plural suffix to the verb is optional. While you will often see -lar/-ler on the verb when the subjects are human, it is still very common and perfectly natural to drop it and just say duruyor instead of duruyorlar.

How is the word paylaşımlar (posts) formed?

It comes from the verb paylaşmak, which means "to share." By adding the suffix -ım, which turns verbs into nouns, we get paylaşım, meaning "a share" or, in modern internet vocabulary, "a social media post." Finally, -lar is added to make it plural.

Since kötü paylaşımlar is the object of the sentence, why doesn't it have the accusative case suffix?