Schefter says the NFL was prepared to suspend Collins five games for missing seven scheduled tests but the NFLPA negotiated a reduction down to two games.
Collins, however, appealed the suspension, arguing that he had valid reasons for missing the scheduled tests.
An arbitrator jointly appointed by the NFL and NFLPA ruled against him and went so far as to reinstate the original five-game suspension.
Collins, 27, signed on with the Cowboys as an undrafted free agent out of LSU in 2015. He was set to make a base salary of $616,750 for the 2017 season when the Cowboys signed him to a two-year, $15.4 million extension through 2019.
Collins is in the second year of his five-year, $50 million deal and was set to earn base salaries of $8,55 million and $10 million over the next two years.
In 2021, Collins has appeared in one game and made one start for the Cowboys.