@Braun, Lena - I assume you are referencing the 1000 users limitation outlined in the How Many Users Can Collaborate on a Board Simultaneously Help Center article: 

We test our app regularly with a higher number of users, but it is too early for us to say that everyone’s’ experience will be seamless if you go over 300 collaborators. The above limit doesn't apply to viewers, so you can invite more of them to observe (with a maximum of 1000 total users per board).

The message shown to the users over the limit

However, I agree that it may not be clear if  “users” are considered “viewers” and therefore no more than 1,000 people can view at aboard at the same time, e.g., you couldn’t share a link to the board in “Anyone with the link → Can view” mode while hosting an event and expect that, e.g., 2,000 people could watch the event. Another example would be trying to use a Miro board as a public website that gets a lot of concurrent traffic.