Better Accessibility for blind users using a projector

[Jonathan-Matthew]

Current behaviour
At our last conference we had a blind user.
He used OpenSlides in Safari with iPhone 12 (IOS 18.1).
He used the integrated VoiceOver-Screenreader and the Fokus Blue 5. Gen Braille display.
He complained that his screenreader got the information from the projector with a large delay. So he had to refresh the side regulary.
Another problem he faced was that visual effects changed the position of the cursor of his screenreader on the website

Additional context
Same user and setup as in #4397