This is false. Safari supports Manifest V2 and has no plans to deprecate it.
I'd guess that you're confused because Safari lacks support for webRequest BlockingResponse: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web...
Just slapping another name on it doesn't make the issues go away.
This is not true either. There are many different aspects to Manifest V3, such as restrictions on script execution.