PHP warning with unparenthesized expressions

Hi,

I have this message after activation :

Deprecated: The behavior of unparenthesized expressions containing both ‘.’ and ‘+’/’-‘ will change in PHP 8: ‘+’/’-‘ will take a higher precedence in /Users/pierreferron/Sites/diving-experience-test.com/wp-content/plugins/cf7-grid-layout/public/class-cf7-grid-layout-public.php on line 944

My environment :
– PHP 7.3
– WordPress 5.4.1
– Contact Form 7 5.1.9
– Polylang 2.7.3

Detail of line 944 :

debug_msg($submitted_fields, 'CF7SG ERROR: Reached max tabs search loop for table field '.$field_name.' (cannot find any new rows above tab '.$tab_idx.' therefor abandoning search for remaining '.sizeof($submitted_fields)-$idx.' regex match in preg_grep result array listed below)');

Just some parenthesis seems to solve the problem :

debug_msg($submitted_fields, 'CF7SG ERROR: Reached max tabs search loop for table field '.$field_name.' (cannot find any new rows above tab '.$tab_idx.' therefor abandoning search for remaining '.(sizeof($submitted_fields)-$idx).' regex match in preg_grep result array listed below)');