Not the US govt. but independent audits of TikTok US from e.g. Oracle which never fully went through.
I find the Tiktok ban more of a geopolitics thing, less of a national security reponse.
You cannot just make assertions about something, and without substantiating them _adequately_, say 'they just told a lie, so everything that they said are lies'.
This is rooted in an anti-China rhetoric and only undermines the US position since for more than a decade many western companies' complaints against Chinese partners were about forced technology transfers.
Edit: correct wording and grammar