How are people showing overtime pay since the 2025 W-2 does not have a code for it?

Ask for the last pay stub for the year.

I am just putting the number in box 14 of the W-2 label as "Overtime".

Edit: my apologies I misread the question.

The amount of overtime will be in Box 14 labeled OBBO Premium with money amount.  This figure represents the amount of overtime not taxable.  

The amount shown will not automatically go to Schedule 1A.  When inputting the W2 info, you need to go down to Section VII Deductible Overtime of the W2 input sheet.  On Block 14C enter 3 times the amount shown in Block 14 Other. This will then compute the correct amount and carry it forward to Schedule 1A.  For example, if Block 14 OBBO Premium shows 2,000.00 you will enter 6,000.00 in block 14C so it will generate the 2000.00 tax free.  If you enter 2,000.00 in block 14C the not taxable amount will generate 666.66 and this will show up as the tax-free amount which is incorrect. 

Proseries would need to modify their program to show when we enter the obbopremium amount, that amount will be the actual tax-free amount, and not reply on us entering 3x the amount.