They thinks its Skrulls but the Skrull thing was done in Fan4 part 2 and I think its smoke and mirrors to hide the main script
a comicbookmovie leak
-"My friend is working on the set design and he said during the first half, the Avengers battle each other and during the final half, they all join together to battle a common foe. And based on a set piece hes working on, a scene takes place in a starship or spaceship that breaks apart."
imo not skurlls
Who else is it if its not the Titan?
The Negative Zone?
Sounds like Thanos to me