It’s fundamentally inefficient. The claims of “green” meat production are greenwashing from the industry. The industry would love for you to believe there is a way that they could clean it up. It takes growing tons of crops just for most of that energy to be lost by the creatures moving around, digesting, etc.

Plant-based foods have a significantly smaller footprint on the environment than animal-based foods. Even the least sustainable vegetables and cereals cause less environmental harm than the lowest impact meat and dairy products [9].

https://www.mdpi.com/2072-6643/14/8/1614/html

Nor is something like grass-fed production a solution when that has even higher emissions due to higher rates of methane production from cows. It also is even higher land demand

We model a nationwide transition [in the US] from grain- to grass-finishing systems using demographics of present-day beef cattle. In order to produce the same quantity of beef as the present-day system, we find that a nationwide shift to exclusively grass-fed beef would require increasing the national cattle herd from 77 to 100 million cattle, an increase of 30%. We also find that the current pastureland grass resource can support only 27% of the current beef supply (27 million cattle), an amount 30% smaller than prior estimates

[…]

If beef consumption is not reduced and is instead satisfied by greater imports of grass-fed beef, a switch to purely grass-fed systems would likely result in higher environmental costs, including higher overall methane emissions. Thus, only reductions in beef consumption can guarantee reductions in the environmental impact of US food systems.

https://iopscience.iop.org/article/10.1088/1748-9326/aad401