I had to do my first two internships in office (started before the vaccine rollout reached my age group, eek) and my experience was pretty similar to what you said. I was given some time in the beginning to get familiar with the codebase but not much mentorship.

Most questions I could only get an answer from was about business requirements because they were either too busy or didn't knew much more about the part I was working on.

Not sure if my situation is usual though, even for interns after COVID started.