My ranger did not encounter that bug but beast summons and certain druid forms do count as crimes in the game. Maybe for whatever reason, the companion is bugging out the crime system, leaving the players faction and becoming part of its own? Summon and shape based Ranger and druid is honestly borderline unplayable without the mod that essentially removes it as a crime.

And honestly, having played ranger until probably halfish of act 2... ranger doesn't only feel bad with no niche it excels at, no powerful feelings abilities, but also just unpolished. Want an archer that does lockpicking, etc? Roll a rogue. Want someone that has first aid and summons? Roll a druid. Want someone that can front line with swords and/or magic ? Go fighter and/or bladelock. I'm honestly thinking about remaking this character as something else but it would be yet another playthrough where I am married to Astarion because rogue is so useful.