It used to cost a lot of energy to create one ETH when it was still Proof of Work. But now it's next to nothing...
That's not how it works at all. After the network has switched to POS, validators receive a reward only for confirming new transactions. Accordingly, the number of new coins has been sharply reduced, since there is now no reward for miners. And now, taking into account the coins being burned, after the London fork, Ethereum will become deflationary.
I also have the same thought that the price will tank hard because it is almost cost nothing to create ETH. Besides, I do not think that London Fork will make ETH deflationary because ETH has no finite supply. Just check the max supply of ETH, it is infinite! I doubt this burning will even make the ETH total circulating supply to shrink. I do not even think that it will nullify the daily ETH coin production.