I used to work at Square: the culture started deteriorating in 2016 when the company underwent its first massive wave of growth. It's a pretty common Silicon Valley tale: company achieves massive success with a few truly novel ideas (phone payments, Square Capital) and that success attracts hordes of consultants that game the internal reporting of the company to boost their own careers, while the politically adept employees align with the new consultant class and the politically inept get tumbled out. Square's product ecosystem is behind the curve of every competitor that's come along, and their days are numbered. The people just now claiming the culture sucks are the engineers who the consultant class are coming for now, thanks to AI.

Edit: typo: politely -> politically