Yep. It isn’t unusual to have contractors ask for a deposit if they are going to work on repairs or updates to your home. But (1) the deposit typically serves the purpose of buying materials to work on your job, and *most importantly* (2) you would have a signed contract with the contractor doing business with you, which protects both parties.
In lieu of having signed contracts in this field, I would never be comfortable with a deposit. What’s the purpose of the deposit? If I’m paying you for time or activities performed, then I will pay you once I’ve received your time and activities performed. If I’m paying you so you’ll trust me, then you’ve already indicated that you don’t trust me, so I’m not comfortable continuing the relationship.
I’m sure there are other views on it, but that outlines why I will never be comfortable with the concept of a deposit.