This is pretty standard for organizations that see a large portion of their revenue during those months. This is especially important for ecommerce-like shopping around the US holidays, for instance. Black Friday, Cyber Monday and every intervening day between Thanksgiving and Christmas and the New Year's holidays.

No daily/sprint code changes, release management, emergency approvals and the like. It works pretty well, no major outages and the site kept taking orders.

Source: worked on high-traffic e-commerce infrastructure around US Black Fridays/Cyber Monday shopping days.

That is the time of year when the vast majority of our business occurs. The systems must be as bug free as possible, so no changes are allowed unless a bug pops up that is mission critical. If that were to happen it would involve huge meetings with tons of conversations and dozens of eyes looking at it, even if it is a simple change on one line of code.

No code changes pushed to production is what I've experienced in such places as a risk mitigation strategy, not that everyone is sitting around twiddling thumbs. Every hour of downtime between Black Friday and Christmas will cost a lot of revenue, and sometimes the company will be working with a skeleton crew for a huge chunk of that time,which makes fixes take longer as a bonus. So why risk it?

This was standard protocol in my org at Microsoft as well. The time was suppose to be spend reviewing tech debt/the years oncall issues and come up with plans for them.