From what I see his name was Jake Li and he was attempting to safeguard endangered species against pesticides. So... His position is now vacant. Guessing Texas couldn't stand for it
He/they released this, so maybe I would have to more digging to gain further understanding.
https://texasfarmbureau.org/epa-releases-final-endangered-species-herbicide-strategy/
Edit: it appears he was "brought in" to that position when Biden entered office, and he is moving to the Department of Interior's fish and wildlife division. I suspect that they knew the upcoming and current cuts to the EPA would thin them out and the Fish and Wildlife department is less likely to be gone after, as that's who you get your hunting/fishing etc licenses from. I imagine the establishment that gives out licenses to shoot animals for fun, isn't likely to be targeted by Republicans