Thanks @jnashhawkins!
I turned off Jetpack’s ‘Site Accelerator (formerly photon). Did not fix the /feed.
I entered the https://www.coldcoffeeblessings.com/feed into the feed cleaner, and though it said it was fixed, the /feed page still is broken.
How do I know which post has the flaky image URL? Sorry, I’m very code illiterate. Thanks for helping!!!