Welcome.
Responses to your follow-up questions:
1) Redemption reported in box 19 code A
2) If, as you stated, there were some additional distributions in 2019 to the exiting member, then the 2018 K-1 is not final.
3) There could be some "internal" accounting adjustments / transfers that will need to be recorded in order to get the capital accounts to conform to the redemption.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
