I took a remote job 8 weeks ago at a high-growth startup as an engineer (no junior / senior modifier). I was fairly aggressively recruited by the CEO. I've only ever worked remotely because of COVID, and this is the first large(r) company I've worked for.I had felt the job was going pretty well -- the tech stack is somewhat unfamiliar so I've been getting up to speed and not as productive as some of my team members, and I'd missed a couple morning standups due to timezone differences and insomnia, but I'd been talking to my coworkers often, video calling, etc., and we seemed to have a good rapport, and they'd complimented me on my work multiple times.I saw a meeting with a person I didn't recognize suddenly appear on my calendar in the morning without any notice. I thought it was weird, but figured they were a new person and we'd just be getting to know each other. They were instead an engineering manager I'd never met before -- not my immediate manager or the CTO.He started talking about my performance being an issue: that I'd been missing lots of meetings, and not completing enough points per sprint. I was taken aback, it was early in the morning, so I mostly just "uh-huh"'d and agreed with what he was saying, which may have been a mistake. The meeting was also only 30 minutes before I had to demo a feature to the engineering team, which ended up being pretty scattershot as a result.After the meeting, he sent an email, cc'd to the CTO, my manager, and HR, basically saying the same things: that I needed to have better attendance at meetings and make a certain number of points per sprint, or my employment would be at risk.I totally understand why those things are important and I've been working on improving both and trying to get up to speed faster, but I was really taken aback by the suddenness: I hadn't heard anything from my manager that there was an issue beforehand (I went back through Teams to check and didn't see anything).Am I misunderstanding the situation, and this is just how large companies work? What should I say to my immediate manager / other people in this story?