When you drop your dog off at boarding or grooming, what do you usually show them for vaccine paperwork — printed copies, something on your phone, or does it depend?

I’ve had a couple of situations where I thought I had the right paperwork, but the place still wanted something different or more specific.

Curious what people have found is the most reliable setup — especially whether having everything in one place on your phone actually avoids issues, or if printed copies are still the safest bet.