Additional features, settings, or issues not covered by specific Microsoft Teams categories
Dear @Gareth Quinn,
Thank you for posting your question in the Microsoft Q&A forum.
Based on your description, it appears that the “Manage what attendees see” controls are no longer available in Teams Webinars, and you can no longer control what attendees see during the event.
For a better understanding of your situation, could you please provide the following information:
Has this issue occurred before, or is this the first time you’ve experienced it?
Are you an attendee or the organizer/owner of this webinar?
If possible, please share a screenshot of the issue (ensure that any private or sensitive information is hidden or removed).
Please note that the more details you can provide, the more effectively I’ll be able to assist you.
In the meantime, you can refer to this article Manage what attendees see in Microsoft Teams
Looking forward to your update.