Payroll instructions still said to use code P, and employers won’t (and shouldn't) correct the w2.
Seems like code p has a dual function this tax year. Glad i’m not a programmer.

See bottom p5-top p6
https://www.ey.com/Publication/vwLUAssets/ey-payroll-year-end-checklist-2018/$FILE/ey-payroll-year-e...