It's probably because they hit a dead end with their approach in terms of improvements. You can only get so far with trying to model a physical system with an insane number of degrees of freedom from simulation (and augmented) data.

More likely because the entire Google organization is refocusing on LLMs.

Also they already got their nobel prize, so the marketing benefit is already maxed out.

They are cracking on with related biology related simulation. Some of it is now proprietary though in Isomorphic Labs.