The problem with Texas’ electric grid is deregulation and privatization run amuck. Electric is very political in Texas there’s a whole bunch of issues swirling around the mess from opposition to “green energy” to the belief the private sector can do a better job than government. And the end result is dividends are being handed out and infrastructure is aging and not getting the upgrades it needs.
Nor is any type of reasonable government oversight and regulation being applied to the power grid in terms of winterization requirement, backup capacity, minimum maintenance requirements, or any other aspect of how power infrastructure (and companies) are regulated in most other states.
Texas under Abbott and GOP basically told the power companies "go do whatever you want" while also cutting off interconnection agreements to other states to provide backup.