We have some buyers who just leave "OK" or "Thanks" or similar slightly underwhelming feedback & used to wonder if something was wrong.

Then we started checking their feedback left for others, & often find that it's the same for everyone.

Some of these are also regular buyers, so obviously not unhappy with their items.

Some people just don't like typing.

As no-one has complained or left negs, just keep doing what you're doing. It's definitely much better & more detailed than many sellers we've come across.