Pols on Nostr: Question to those who run a public relay from someone who is not running a public ...

Question to those who run a public relay from someone who is not running a public relay(sorry in advance if the question comes off rude in anyway). What is the reason for the recent widespread turning off of some public relays? Is it just not affordable to run one, or is it something else? Curious since it seems like some public relays are going offline permanently, and it's sad to see that as I feel the more relays there are, the more decentralized nostr is.