I also work at a startup that switched from Next.js to Astro.js.

It was around the time of Next.js 12 -> 13 transition. The overall DX was really bad for us when 13 came out and we had struggled with integrating some third party libraries with 12 (Algolia) and decided to move on.

If you look at who's using Next.js, you'll see dotcoms like Target.com and Walmart.com are both on Next.js as well as many big name e-commerce retailers. That should tell you about the target audience for Next.js. If you balk at using SAP, Oracle, SharePoint, Teams, or Documentum, then you probably shouldn't use Next.js either.