I just did very cursory reading on this, but apparently "Return of Capital" dividends aren't subject to dividend withholding tax at all, and the various Yieldmax ETFs seem to report >90% return on capital in their recent filings.
(I don't know whether that's an indicator of poor performance or not, since it sounds like they're reducing the NAV and distributing the principal as "income", like the other "income" funds here.)
Data points seem to suggest that IBKR returns any withheld tax once it receives the 1099 filing from Yieldmax.
The estate tax concern still applies, of course.
