bp_groups_format_activity_action_joined_group( string $action, object $activity )

function bp_groups_format_activity_action_joined_group( $action, $activity ) {
	$user_link = bp_core_get_userlink( $activity->user_id );

	$group      = groups_get_group( $activity->item_id );
	$group_link = '<a href="' . esc_url( bp_get_group_permalink( $group ) ) . '">' . esc_html( $group->name ) . '</a>';

	$action = sprintf( __( '%1$s joined the group %2$s', 'buddyboss' ), $user_link, $group_link );

	// Legacy filters (do not follow parameter patterns of other activity
	// action filters, and requires apply_filters_ref_array()).
	if ( has_filter( 'groups_activity_membership_accepted_action' ) ) {
		$action = apply_filters_ref_array( 'groups_activity_membership_accepted_action', array( $action, $user_link, &$group ) );
	}

	// Another legacy filter.
	if ( has_filter( 'groups_activity_accepted_invite_action' ) ) {
		$action = apply_filters_ref_array( 'groups_activity_accepted_invite_action', array( $action, $activity->user_id, &$group ) );
	}

	/**
	 * Filters the 'joined_group' activity actions.
	 *
	 * @since BuddyPress 2.0.0
	 *
	 * @param string $action   The 'joined_group' activity actions.
	 * @param object $activity Activity data object.
	 */
	return apply_filters( 'bp_groups_format_activity_action_joined_group', $action, $activity );
}