For some reason being at the table seems like it’s really overwhelming and stressful for her. It could be a combination of being tired and having to process multiple conversations etc when she’s exhausted from the day. Being the youngest she might feel like she has to fight for attention. If she doesn’t have to eat at the table when she’s with her other parent she might prefer this and be doing everything in her power to make eating together unpleasant for everyone. I hope you get to the bottom of it soon.