横から失礼いたします。

私も同じ問題で困っているので、こちら参考にさせていただきたいです。

私もxdebugを無効にする方法がよくわからいのですが、教えていただけますでしょうか？

memory_limitが128M -> memory_limitを512M
max_execution_timeが30 -> max_execution_timeを180
composer.lock　→666
composer.json　→666
はいずれも対応済みです。

それ以外ではこんなエラーが出ています。

Deprecation warning: require.ec-cube/CartClearV4 is invalid, it should not contain uppercase characters. Please use ec-cube/cartclearv4 instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require.ec-cube/ECCUBE4LineLoginIntegration is invalid, it should not contain uppercase characters. Please use ec-cube/eccube4lineloginintegration instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require.ec-cube/MGSocialButton is invalid, it should not contain uppercase characters. Please use ec-cube/mgsocialbutton instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require.ec-cube/MailMagazine4 is invalid, it should not contain uppercase characters. Please use ec-cube/mailmagazine4 instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require.ec-cube/Maker4 is invalid, it should not contain uppercase characters. Please use ec-cube/maker4 instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require.ec-cube/ProductReview4 is invalid, it should not contain uppercase characters. Please use ec-cube/productreview4 instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require.ec-cube/RecommendedProducts4 is invalid, it should not contain uppercase characters. Please use ec-cube/recommendedproducts4 instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require.ec-cube/RelatedProduct4 is invalid, it should not contain uppercase characters. Please use ec-cube/relatedproduct4 instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require.ec-cube/SprocketTag is invalid, it should not contain uppercase characters. Please use ec-cube/sprockettag instead. Make sure you fix this as Composer 2.0 will error.
Deprecation warning: require-dev.mikey179/vfsStream is invalid, it should not contain uppercase characters. Please use mikey179/vfsstream instead. Make sure you fix this as Composer 2.0 will error.
PHP Parse error: syntax error, unexpected 'class' (T_CLASS), expecting identifier (T_STRING) or variable (T_VARIABLE) or '{' or '$' in /home/drugpure/drugpure.jp/public_html/vendor/ec-cube/plugin-installer/src/Eccube/Composer/PluginInstaller.php on line 72

Parse error: syntax error, unexpected 'class' (T_CLASS), expecting identifier (T_STRING) or variable (T_VARIABLE) or '{' or '$' in /home/drugpure/drugpure.jp/public_html/vendor/ec-cube/plugin-installer/src/Eccube/Composer/PluginInstaller.php on line 72

宜しくお願い致します。