Correct in that moment. But make sure you are in a very healthy place first. Once something is said you can't ever take it back.

We would have partners that would be so negative it would bring down the entire shift.

I once was snapped at by a barasita because on CS I was asking her (on bar) if she needed anything "too much" she raised her voice at me saying "stop asking me I'll just tell you when I need something!", This is after her snapping at 4 other partners. I told her right than calmly

"Hey X partner, I get that you are stressed out right now, and you're grumpy right now but you will not talk to me that way ever again. I respect you, please show me that same respect back. I'm here to help and I'm sorry I'm annoying you, next time just tell me that instead in snapping and almost yelling at me and everyone else "

I feel like it always helps having good relationship with your partners, and always being able to admit when you are crabby to and to apologize early and often, or just be quit till you have something better to contribute

When you talk to someone, always do it in private. Otherwise, you're putting them on the defensive. Never confront. Then you're just dealing with egos. But talk to them. It talk to them with a manager present so it's recorded. Or record the conversation. Don't share it either.

I had (have? Still not clear on if she quit or if she just took time off cause she has other jobs) a coworker who was rude to me since my first day. One day, I decided to just talk to her the way she talked to me, and needless to say, she was not a fan of that. Any time I’ve worked with her since then, she only talked to me as much as was necessary lol

Ideally you'd speak to your manager about the behavior and the manager would then work with the barista to either adjust their behavior or leave the company.

Realistically do that but as an entire team. Put your collective foot down.