Why do some tips go to my creator dashboard but some go to my exchange account?
There are two kinds of BAT - virtual BAT and real BAT.
Tips that go into your Creator dashboard are from unverified users. These users have not connected their browser to a partner exchange yet. Tips from unverified users are virtual BAT managed entirely on Brave's own infrastructure, and do not become real BAT (on the Ethereum network) until your monthly payout.
Tips that go directly to your exchange account are from verified users. These users have connected their browser to a partner exchange, and so the BAT in their account is real BAT. Real BAT needs to be transferred on the Ethereum network, so the tip goes directly from their exchange account to your exchange account.