Yes. 1.31 is EOL, this is why we upgraded to 1.35.4. Precondition for MW 1.35 is PHP 7.3+, so additionally we upgraded to PHP 7.4.24. Whilst we *never* had a similar warning with 1.31.15 and PHP 7.2.24, *now* we have a PHP warning using the script with MW 1.35.4 and PHP 7.4.24.
So maybe the issue may have been fixed in 1.32, but surely it is *not* fixed in 1.35.4. Hope the description is clear now?
Closing the request without having understood it is, let us say, a little bit impolite.