I also submitted a Feedback Report back on March 25th, FB13697245.

I reached out to them on March 17, and on March 27, they requested a screenshot along with steps to reproduce the issue. I responded immediately. However, since then, there has been no response from Apple. The problem continues and is affecting our sales😔

The German version.

Hi all, The problem fixed itself after about 6 hours. We noticed other apps had the same issue, so it might've been a glitch with Apple's in-app purchase system during that time. Best, Juno

The issue is now resolved.