For the Quantum Suits, Jen Underdahl and company tried to combine the technology of all the tech-based heroes. This includes the Guardians of the Galaxy, and the mesh that allows the cosmic characters to breathe in space. The mesh acts like a bubble around characters’ full bodies, but it didn’t translate well for the Endgame‘s suits. Instead, the Ant-Man helmet was added, and creating a more exciting visual effect in the process.
Article source: https://www.cinemablend.com/news/2480208/avengers-endgames-quantum-suits-were-almost-inspired-by-guardians-of-the-galaxy