yakovklein

To allow use with username Hebrew add this filter in functions.php file

add_filter( 'sanitize_user', 'sanitize_user_with_hebrew', 10, 3 );

function sanitize_user_with_hebrew( $username, $raw_username, $strict ) {

	$username = $raw_username;
	$username = wp_strip_all_tags( $username );
	$username = remove_accents( $username );
	// Kill octets
	$username = preg_replace( '|%([a-fA-F0-9][a-fA-F0-9])|', '', $username );
	$username = preg_replace( '/&.+?;/', '', $username ); // Kill entities

	// If strict, reduce to ASCII for max portability.
	if ( $strict ) {
		$username = preg_replace( '|[^a-z0-9א-ת _.\-@]|i', '', $username );
	}

	$username = trim( $username );
	// Consolidate contiguous whitespace
	$username = preg_replace( '|\s+|', ' ', $username );

	/**
	 * Filter a sanitized username string.
	 *
	 * @since 2.0.1
	 *
	 * @param string $username     Sanitized username.
	 * @param string $raw_username The username prior to sanitization.
	 * @param bool   $strict       Whether to limit the sanitization to specific characters. Default false.
	 */

	return $username;
}