Here's what the wiki says about Terrion Arnold's situation (from the Terrion Arnold page):
He was arrested and charged with four counts of kidnapping and four counts of armed robbery stemming from a February 4, 2026 incident in Tampa, Florida. He's accused of orchestrating a targeted robbery and faces potential life in prison. Prosecutors have argued he should be held in jail until trial.
As for the 2026 season, his status is described as "in serious jeopardy pending the legal process" — the Lions have declined to comment, saying they're respecting the ongoing legal proceedings. The wiki doesn't mention any formal NFL suspension being handed down yet; it's more that his availability is completely unknown while he's fighting these felony charges and potentially staying in jail. A suspension (whether from the NFL or simply due to being incarcerated) seems very likely, but there's no final ruling on the books as of the wiki's latest update.
Bottom line: Don't count on him playing in 2026 — this is a life-altering legal situation, not a routine league discipline matter.