amzd

It can also mean to overcharge someone,

But does that make sense in the context that Jesus said it? Jesus whole thing was being compassionate, not the cost of living. A week later on his last meal he even famously rejected the lamb from his final meal.

what were they stealing from the animals

Their lives

He calls them “λῃστής”

Even in the source you linked that is translated to robber. To rob means “stealing using force or violence”. Who were the priests using violence against you think? Their clients or animals?

He called out the practice of killing animals for money, specifically calling the priests murderers during the event you reference. Not much of that spirit left in modern churches.