If you want to send a site-wide notice, Go to WordPress Toolbar >> Messages >> Site Notices on the WordPress Backend.
This notice will display on the BuddyPress profile of every Loggedin member.
Site wide Notices
Update on May 27, 2022
If you want to send a site-wide notice, Go to WordPress Toolbar >> Messages >> Site Notices on the WordPress Backend.
This notice will display on the BuddyPress profile of every Loggedin member.