Not to worry! Your situation is fairly common, as the plant material takes on some of the liquid it expands and can become exposed where it was originally covered. This isn’t too much of a problem, especially if it has only been macerating for 10 days.
What you can do is open it up, look at it and smell it to check for any mould (it’s unlikely). If it seems okay, then add more vinegar into the jar so that the plant material is fully covered again and continue to macerate for the length of time originally intended.
For future vinegar making and tincturing/oils etc. Let it sit for 24-48 hours then check and top it up to cover if needed. If you are following ratios, then measure what you add to top it up so that you can keep track of your ratio/strength.
I hope your vinegar is still good and that you have great success with future macerations as well!