I have been full-time on Ethereum for years, I'm a software engineer, and I have a relatively intimate knowledge of the specific milestones the community has been achieving and why that implies that proof of stake will ship this year.

Here's an overview

Dec 2020: proof of stake launched in production, but isn't yet used to secure ethereum, it runs in parallel

October 2021: the last major upgrade to Ethereum before switching to proof of stake went live in production

Today: proof of stake "Merge" testnets are live, all core teams are 100% focused on the merge, regular progress reports are nominal, etc.