Code P is where an employer provides reimbursement under an accountable plan for qualified moving expenses.  Based on Notice 2018-75, Code P is still applicable to non-military moves as in the case of the OP.

Intuit has taken an incorrect position, not only in PS but also in PTO (and possibly Lacerte) to add the amount in Code P to Box 1 and report that on Line 1 of F.1040.  In PTO, it also assumes FICA had been withheld on the Code P amount and subjects the same to additional medicare tax on F.8959 (although I'm not sure if it does the same on PS).

Given how this has been programmed, backing the amount out on Line 21 is not a viable solution both in terms of presentation and tax impact.  Intuit will need to fix this asap.