>a project manager vibe-coded the change without thinking it through at all

The PMs vibe-coding and having no idea what they're doing isn't even the main issue (although it is pretty bad).

The main issue is: how are the actual engineers supposed to "review" the slop? They probably report to the same PM or are at below in the org chart and might be evaluated by them. Not just at MS, but any company.

Such a conflict of interest would be detrimental to quality anywhere. You wouldn't build a bridge like this, nor should you software.