Fine clarification as it pertains to all players, including rookies but in this case specifically rookies, per the NFL/NFLPA CBA (
link):
ARTICLE 42, CLUB DISCIPLINE, Section 1. Maximum Discipline, (b) 2020-2021 League Years
(vi) Unexcused late reporting for or absence from preseason training camp by a player under contract except those signed as (1) an Unrestricted Free Agent pursuant to Article 9; or (2) a Drafted or Undrafted Rookie pursuant to Article 7—mandatory fine of $50,000 per day. For the avoidance of doubt, any such fines shall be mandatory, and shall not be reduced in amount or waived by the Club, in whole or in part, but must be paid by the player or deducted by the Club as provided in Section 5(b) of this Article. For purposes of this Subsection (vi) and Subsections (vii)-(ix) below, preseason training camp shall be defined as the period beginning with the mandatory reporting date for any player through the Sunday immediately preceding the first game of the NFL regular season.
(viii) Unexcused late reporting for or absence from preseason training camp by a player under contract signed as a Drafted or Undrafted Rookie, pursuant to Article 7, except for a player in the fifth League Year of his Rookie Contract (the option year) after his Club has exercised the Fifth-Year Option pursuant to Article 7, Section 7— fine of $40,000 per day.
(ix) Unexcused late reporting for or absence from preseason training camp by a player in the fifth League Year of his Rookie Contract (the option year) after his Club has exercised the Fifth-Year Option pursuant to Article 7, Section 7 shall subject the player to the discipline set forth in Article 7, Section 7(h).
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All of the above applies to CeeDee Lamb's fine situation unless the CBA states somewhere else that rookie fines can be forgiven--which I would be personally interested in reading. Fines are not
forgiven according to the language of the CBA. Either the player pays their fines or their team deducts the amount of the fines.