In an article from Travel Weekly, Lufthansa Group said it is facing "steadily rising additional costs due to regulatory environmental requirements." These include the EU's new 2% blending quota for sustainable aviation fuel (SAF) from 2025, adjustments to the EU Emissions Trading System and the costs complying with CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation).
Regulations will mandate the use of SAF's in the future and while airlines heavily invest in new aircraft and other measures to make flying more sustainable, these additional costs will no doubt eventually be passed on to the consumer.
See the Travel Weekly article HERE