Array and string offset access syntax with curly braces is deprecated in PHP 7.4. Use square brackets instead. Seen for $path {(strlen($path) - 1)}

Problem/Motivation

I catched a PHP7.4 notice deprecation

Array and string offset access syntax with curly braces is deprecated in PHP 7.4. Use square brackets instead. Seen for $path {(strlen($path) - 1)} 
../pdf_using_mpdf/pdf_using_mpdf.module 428

See https://wiki.php.net/rfc/deprecate_curly_braces_array_access

Steps to reproduce

Switch to php7.4, check logs

Proposed resolution

I would suggest to apply a patch