I've been using Bun since 2022 just to be trendy for recruitment (it worked, and still works despite it almost being 2026)

Bun is fast, and its worked as a drop in replacement for npm in large legacy projects too.

I only ever encountered one issue, which was pretty dumb, Amazon's CDK has hardcoded references to various package manager's lock files, and Bun wasn't one of them

https://github.com/aws/aws-cdk/issues/31753

This wasn't fixed till the end of 2024 and as you can see, only accidentally merged in but tolerated. It was promptly broken by a bun breaking change

https://github.com/aws/aws-cdk/issues/33464

but don't let Amazon's own incompetency be the confirmation bias you were looking for about using a different package manager in production

you can use SST to deploy cloud resources on AWS and any cloud, and that package works with bun