Same issue as Gallery View Button not showing in Chrome Browser - Web Client SDK - Zoom Developer Forum.
Those who have earlier version of web sdk will have to update to at least 1.9.5 and fix if running in “web isolation or using SharedArrayBuffer” I believe. We just found this so if edge or chrome was updated as our was last friday, also note you have no button top right to change view from speaker view - seems like this is the issue. We will investigate here in next day, let me know what you find.