I am not sure if I did something wrong or what triggered this behaviour but let me describe what I did and what happened:
I selected one folder > clicked share with users > add users > add guest user > added the name and email of user A > added the name and email of user B > adjusted the permissions of both to download only and clicked apply.
Furthermore, I then checked the emails which were sent out to see if they were properly sent and found two outgoing emails:
Email a) was sent to user A and email b) was sent to user A AND user B both directly addressed in the TO: section.
Now this is not a problem as I was sharing with both of them intentionally, and they are one team, but I suppose the emails to multiple people should not be sent out together, right?
Here is what it looks like on Gmail as I use their SMTP server:
Customer support service by UserEcho