The IRS has all of the Codes for each line in the K-1 Instructions for 2020. The draft Schedule K-1 instructions state no "page 2" of the Form and to review the codes as listed in the instructions. There are many more Codes that have been added for 2020. I'm guessing they couldn't list all the codes on one page so they decided to include in the instructions instead.
Nope, doesn't exist for 2020.
Also, the Codes listed in the DRAFT Schedule K-1 instructions for Partnerships start on page 21 and end on page 24. The Codes have a column for Where to report on your return and refers back to other pages of the Schedule K-1 instructions.