Mixed shadow mode is available as a developer preview with Sprint'23 release
Build Components in Mixed Shadow Mode (Developer Preview) With mixed shadow mode, Lightning web components can use native shadow DOM even when the synthetic shadow polyfill is applied. Where: This change applies to custom Lightning web components in Lightning Experience, Experience Builder sites, and all versions of the Salesforce mobile app. This change also applies to Lightning web components open source. NOTE Mixed shadow mode is available as a developer preview. This feature isn't generally available unless or until Salesforce announces its general availability in documentation or in press releases or public statements. All commands, parameters, and other features are subject to change or deprecation at any time, with or without notice. Don't implement functionality developed with these commands or tools. Why: All major browsers now support shadow DOM . Salesforce maintains the synthetic shadow polyfill for legacy browsers such as older ver...