Sarah Kobos, a senior photo research coordinator on Jimmy's talk show, ripped him Tuesday on social media as the writers' strike began, saying ... "He wasn't even at the meeting this morning to tell us we won't get paid after this week."

Sarah tagged Jimmy in her tweet, adding ... "@jimmyfallon please support your staff. Had fun bowling with ya last week, but a fun party won't pay my rent."

Jimmy, like all other late-night hosts, is scrambling to figure out how to handle personnel matters during the writer's strike, which will affect all employees -- including non-writers -- because all the network talk shows are shutting down.

Monday at the Met Gala, Jimmy was asked about the strike and told Variety, "I wouldn’t have a show if it wasn't for my writers, I support them all the way."

In follow-up tweets, Sarah says she's not a striking worker because she isn't a member of the Writers Guild of America, but again ... with all the shows airing reruns, her livelihood will be impacted nonetheless.

She adds 'Tonight Show' employees were told "NBC decided to stop paying us after this week and end our health insurance after this month if the strike is ongoing. They won't even tell us if we will technically be furloughed. Just active employees who aren't paid."

Fairly or not, Sarah also openly compared Jimmy to Seth Meyers, who hosts 'Late Night' on NBC ... saying she was told Seth was on a Zoom meeting telling his staff and crew he would try to take care of them financially "after NBC stops paying."