Money

Car companies (According to the article Volkswagen AG (Volkswagen, Audi, Porsche), Stellantis (Peugeot, Citroën, Fiat, Opel), BMW, Renault) want to keep selling petrol vehicles, because they have a smaller profit margin on EVs than they do on petrol vehicles.

The smaller profit margins also spook legislators in certain countries (particularly those with a large car manufacturing industry) because the car companies employ a lot of people there. Lawmakers from countries like Germany and Italy (Volkswagen, Audi, Porsche, BMW, Opel, Fiat, etc) were never fully on board with the 2035 combustion engine ban, and they are now trying to push the EU to reconsider it.

France and Spain (Peugeot, Citroën, Renault, Seat, etc.) are in favour of the combustion engine ban staying in place, but they would like to see some flexibility on the specifics.

Meanwhile critics argue that scrapping, delaying, or watering down the combusion engine ban means that European car industry will have less of a drive to innovate on EVs, which in turn would cause the gap between them and the Chinese car industry to widen.
EVs are the future and we need to be competitive on that front.

Edit: It’s all a bit disappointing, because many of these car companies do actually have very compelling and competitive EVs on the market at the moment. It’d be a shame to not keep that momentum going.