Detroit was one of the teams running tight on cap space to finish out the regular season.
Vaitai, 28, was drafted by the Eagles in the fifth round out of TCU in 2016. He signed a four-year deal worth $2.56 million and made a base salary of $720,000 for the 2019 season.
Vaitai was testing the market as an unrestricted free agent for the first time in 2020 when he signed a five-year, $50 million deal with the Lions.
In 2021, Vaitai has appeared in 14 games and made 14 starts for the Lions.