The W-4 change happened in 2020.  The "new and improved" form was redesigned to give taxpayers more money in their paychecks rather than using the IRS as a savings account.  There was an informal transition period as payroll software slowly got updated/reprogrammed.  Most employers within the past couple years required employees to fill out new W-4 forms as their software no longer supported the "old" calculation.

I'm also seeing these transitions with the "new and improved" W-4P so it'll hit your 1099-R folks as well.  You know, just in time for personal exemptions to come back in 2026, right?