The EligibleForShopifyTaxReporting and ShopifyTaxReportingLegacyAutoTaxMigrated fields have been removed from the ShopFeatures object as it is no longer utilized in Shopify tax reporting. There are no replacements for these fields for external-facing apps. If you rely on these fields, you should update your integration accordingly.
This is a companion discussion topic for the original entry at https://shopify.dev/changelog/removed-tax-related-fields-from-the-shopfeatures-object