The file https://github.com/ibexa/post-install/blob/906589a8dd52e1f46b7613f81fb0cb7f36821103/resources/platformsh/common/4.5/.platform/services.yaml#L79 refers to app/config/env/platformsh.php, but the logic in that file was moved to vendor/ezsystems/ezplatform-core/src/EzPlatformCoreBundle/bundle/DependencyInjection/EzPlatformCoreExtension.php in Ibexa DXP 3.x and to vendor/ibexa/core/src/bundle/Core/DependencyInjection/IbexaCoreExtension.php in Ibexa DXP 4.x