One of the core problems with capitalism is that it's fundamentally based on growth and consumerism. Companies need to constantly sell products in order to continue to operate and this leads to things like planned obsolescence where goods are intentionally manufactured to break so that new ones could be sold. This is just one of countless examples of perverse incentives that capitalism creates.

On the other hand, socialism creates a completely different incentive structure. Things are produced based on societal needs, and producing things is seen as a cost. This creates incentive to make things that last, and that can be repaired. Here's a great article explaining how this worked in practice in USSR.

So, while socialism alone doesn't ensure sustainability, it doesn't create perverse incentives that capitalism creates, and it makes it possible to have a sustainable economy.

For example, capitalists would hoard land to seek ransoms in exchange of its access. This causes land unaffordability and under usage. If socialism eliminates that, more land might be used and there might be more environmental destruction as a result.

I don't think that's true. Underused land is not necessarily protected, for example, you can dump chemical waste on a plot of land and that makes you money without developing it. Industrialized farming uses a lot of pesticides and takes up a huge amount of land without caring too much about individual plants bc of quantity over quality. Meanwhile people still have to live and work somewhere, and there's no guarantee that that somewhere will be less environmentally destructive.

I would agree that socialism has potential to be ecologically destructive but I disagree that capitalism does anything innately that protects the environment.