Why can't I delete some sites listed under "Sites that can always use cookies"?

You can only delete entries in this list that you have created yourself. Any entries automatically added by Brave for the reasons below can only be removed by disabling/removing the reason they were added in the first place.

 

Google login button cookies

The cookie allowances for https://[*.]firebaseapp.com and https://accounts.google.com in the list of sites that can always use cookies are required by the "Allow Google login buttons on third-party sites" feature, and to delete them you need to disable this feature.

You can find it under Settings->Social media blocking (or navigate to brave://settings/socialBlocking) on desktop, or Settings->Brave Shields & Privacy->Social Media Blocking on Android (possibly also on iOS but I won't have access to a test device for a while).

Disable the feature, then you should be able to go back the to list of permanently allowed cookies and the two entries should automatically be gone.

 

Cookies from Brave Shield settings

If you have dropped your Brave Shields, or set Shields to allow cookies, for any specific sites they will also appear in this list, and cannot be removed.

You have to navigate to that site and raise your Shields again, or set Shields to block cookies or block cross-site cookies, then the entry will be removed from the list.

 

There may also a bug with Brave Sync that can cause entries in this list to not be deletable, or to return after deletion. [Current August 31 2021 - status unknown at March 29 2022 - have not heard reports of this issue for a long time]