I found false positive at Google for woocommerce plugin:
PHP 8.0 incompatibilities:
FILE: vendor/phpseclib/phpseclib/phpseclib/Crypt/Common/SymmetricKey.php
FOUND 46 ERRORS AND 0 WARNINGS AFFECTING 26 LINES
1278 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1278 | ERROR | Function mcrypt_generic_init() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1311 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1311 | ERROR | Function mcrypt_generic_init() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1314 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1314 | ERROR | Function mcrypt_generic() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1319 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1319 | ERROR | Function mcrypt_generic() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1328 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1328 | ERROR | Function mcrypt_generic() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1340 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1340 | ERROR | Function mcrypt_generic() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1343 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1343 | ERROR | Function mcrypt_generic_init() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1669 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1669 | ERROR | Function mcrypt_generic_init() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1697 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1697 | ERROR | Function mcrypt_generic() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1702 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1702 | ERROR | Function mcrypt_generic() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1713 | ERROR | Function mdecrypt_generic() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
1716 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
1716 | ERROR | Function mcrypt_generic_init() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
2269 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
2269 | ERROR | Function mcrypt_list_algorithms() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
2384 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
2384 | ERROR | Function mcrypt_module_close() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
2385 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
2385 | ERROR | Function mcrypt_module_close() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
2390 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
2390 | ERROR | Function mcrypt_module_close() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
2503 | ERROR | The constant "MCRYPT_MODE_ECB" is deprecated since PHP 7.1 and removed since PHP 7.2
2504 | ERROR | The constant "MCRYPT_MODE_CBC" is deprecated since PHP 7.1 and removed since PHP 7.2
2506 | ERROR | The constant "MCRYPT_MODE_CFB" is deprecated since PHP 7.1 and removed since PHP 7.2
2507 | ERROR | The constant "MCRYPT_MODE_NOFB" is deprecated since PHP 7.1 and removed since PHP 7.2
2508 | ERROR | The constant "MCRYPT_MODE_OFB" is deprecated since PHP 7.1 and removed since PHP 7.2
2509 | ERROR | The constant "MCRYPT_MODE_STREAM" is deprecated since PHP 7.1 and removed since PHP 7.2
2512 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
2512 | ERROR | Function mcrypt_module_open() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
2513 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
2513 | ERROR | Function mcrypt_module_open() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
2519 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
2519 | ERROR | Function mcrypt_module_open() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
2519 | ERROR | The constant "MCRYPT_MODE_ECB" is deprecated since PHP 7.1 and removed since PHP 7.2
2524 | ERROR | Extension 'mcrypt' is deprecated since PHP 7.1 and removed since PHP 7.2; Use openssl (preferred) or pecl/mcrypt once available instead
2524 | ERROR | Function mcrypt_generic_init() is deprecated since PHP 7.1 and removed since PHP 7.2; Use OpenSSL instead
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