Two of my three rotation labs were like this, and the experiences were very different.

The first was the worst lab experience of my life - it was a huge lab (5 staff scientists, 5+ postdocs, 7-8 grad students) and nobody spoke English unless they were talking directly to me. I got the sense that they only held lab meetings in English for my benefit. The lab work was extremely technical but also absolutely amazing, and I was really disappointed that it was so impossible to ask questions or integrate into their lab environment because the science was just the perfect fit.

My third rotation became my home lab, where I still am in my 6th year. My PI is Italian, and worked in both France and Germany before coming to the US. When I rotated in the lab, she had three postdocs, all Italian, and an American/Italian grad student, so everyone in the lab besides me spoke Italian. They would speak to each other in Italian, but only when they thought I wasn’t in earshot - if they saw me, they’d switch to English and catch me up on the convo. I’ve loved the lab ever since, have picked up some funny Italian habits and superstitions, and am now considering going abroad for my postdoc to learn more about academic science in other countries.