"For each website receiving votes during a Calculation Period that is not a Brave Publisher by the end of that Calculation Period, the BAT corresponding to its votes will not be distributed at the end of that Calculation Period, and will instead be held in an Uphold omnibus wallet for no less than ninety (90) days thereafter. At that time, the undistributed BAT may be sent to Company’s user growth pool, which is a pool of BAT that Company administers to incentivize use of the Platform (as described more fully in Exhibit B of the BAT Terms of Sale, available at https://basicattentiontoken.org/terms-and-conditions/). But if the website receiving votes becomes a registered Brave Publisher before the corresponding BAT is sent to the user growth pool, that website will receive such BAT as Publisher Contributions in the first Calculation Period following its registration."
So if you donate money to a content creator that hasn't signed up to be a Brave publisher (and in doing so, agreed to Uphold's ToS), your donation will go to the "User Growth Pool". From their regular ToS:
"Once the User Growth Fund is exhausted, it will be discontinued, and no new BAT will be created for or transferred to the User Growth Fund"
So who knows where your donations will go if the content creator doesn't sign up to receive them.
[0] https://basicattentiontoken.org/contributor-terms-of-service...