I think I'd be more worried about my job in a 10000 person company than a 300 person company.

If Im in a 300 person company I'm probably one of 40-60 devs, and most of my peers know me and have met me. If I'm a senior dev, there's a good chance I'm on first name basis with the executive team, and they know what I work on and the impact I have. There's a lot better chance of me being able to demonstrate my value and avoid being let go if cuts are needed.

At a 10000 person company I'm basically guaranteed to just be an employee number next to a salary number in a spreadsheet, when it comes time for cuts.