Room IDs in Matrix have changed from a format like !XobthiyrsXshZCJPxh:privacyguides.org to a format like !0EgO6JUj4upTN5XF70_Ox0Wg0gFVD8WKJxIdFGiYL_4 following a security release on August 11th.
Subsequently, rooms on Matrix are no longer able to be added in the chat integration plugin due to the input field validation: