System informations:

• OS: Debian 10
• Composer version: 2.0.9-2

Done steps:

• installed fresh version of Composer from Debian repository (version as described above)

Terminal output while usage:

Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:51
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:51
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:52
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:54
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:56
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:51
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:52
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:54
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:56
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:51
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:52
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:54
Deprecation Notice: preg_match(): Passing null to parameter #4 ($flags) of
type int is deprecated in /usr/share/php/Symfony/Component/Console/Input
/StringInput.php:56