W-9 mismatch → IRS exposure
A foreign-owned SMLLC is a disregarded entity. The foreign owner is the taxpayer. A foreign person cannot legally certify as a U.S. person on a W-9.
TikTok will accept a W-9 from anyone. They do not verify whether you filled it out correctly. You just signed a federal tax document under penalty of perjury. TikTok will not catch this. The IRS will.