Polygon is behind a lot of the ZK-SNARK and ZK-STARK research, and I believe they have several Layer 2s in development based on that technology (as well as the separate PoS network, Polygon, which is checkpointed to the mainnet).
I'm surprised they only have 500 employees to be honest, but there's a good chance a lot of the work in the space is done in collaboration with other companies and open source contributors