Peters was placed on the 10-day injured list Friday with a lower-back strain, Alex Stumpf of DKPittsburghSports.com reports.
Peters apparently suffered the injury during Monday's start against the Reds, when he gave up four runs on four hits with three strikeouts and two walks. The left-hander will be eligible to return before the end of the season (assuming the move is retroactive), though it's unclear if he's expected to be activated for one final start in 2021.