So some dividend information has been updated at vanguard.com
I would like to contrast how Vanguard presents information differently for the mutual fund and the ETF with VTSAX / VTI as examples:
A consequence is that the mutual fund shareholder received the information too late to make an informed decision about avoiding the dividend. The ETF shareholder can sell the ETF shares and buy the mutual fund shares on Monday 6/13 and avoid the dividend.
Also note some terminology differences. Other mutual fund companies will use "ex-dividend date" for their mutual funds. Vanguard does not. And if one has ETF dividends automatically reinvested, what is the Reinvest date for that? Answer: It depends on your broker. Note that one not reinvesting dividends will get their money a week later with the ETF.
I wonder if a thread gets started with the question "Why did VTSAX change more percentage-wise today than VTI? Aren't they the same?" It is possible that on Monday 6/13 one of them goes up and one goes down. And maybe vice versa on Tuesday.
Bonus comment: Folks who tax-loss harvested VTSAX and exchanged into VFIAX can avoid the dividends of both these funds by exchanging back from VFIAX into VTSAX early next week. I'm not sure why one would want to do that though with the nice gains that they should have after the TLHing.