Because high energy prices don't fight climate change directly. All the higher prices do is hurt the economy as it makes everything more expensive to buy. It is the same reason they can't just shift over to green energy as the impact would be very bad for the economy.

What is needed to fight climate change is to reduce the costs and increase output of green energy so that it can replace existing sources.

This question shows why higher energy prices are not a way to fight climate change. Germany (and other countries) are trying to find ways to help their citizens pay for the energy they use after the sharp increases in prices. Those higher prices only reduce the use of that energy so far. It also increases the profits of the companies involved allowing them to spend more money on the same fuels.

[Why is Germany subsidizing the cost of electricity for everyone rather than only the poorest households?][1]

As long as those fuels are profitable they will still continue to be used.

  [1]: https://politics.stackexchange.com/questions/75849/why-is-germany-subsidizing-the-cost-of-electricity-for-everyone-rather-than-only