Brave Shields are set to block all cookies browser-wide. I have granted cookie permissions to the specific handful of sites I need them for.
But specific Brave extension (Feedbro, a multi-use local feed reader) requires Brave to allow cookies in order to access my Instagram cookies to fetch Instagram posts. Allowing cookies on Instagram itself doesn't matter.
The issue seems to be that with Brave set by default (browser wide) to block cookies, the extension can't access the allowed Instagram site cookies. And extension pages chrome-extension://mefgmmbdailogpfhwrjsbrnjfmnpnmdfa seem to have no way of setting specific Brave Shield controls for them. The only settings adjustment I've found that gets this working is to change "Block Cookies" in brave://settings/shields from "All" to "Cross-site". But of course that allows all 1st party cookies now on every site, browser-wide.
How can I allow just this extension and its page to have full cookie access? I tried adding an exception rule like @@||chrome-extension^ or the specific extension URL but no luck.
I seem to have figured it out.
Go to the Brave cookie settings page at brave://settings/cookies
Under the "Sites that can always use cookies" list, I manually added these entries, allowing 3rd party cookies too:
[*.]mefgmmbdailogpfhfblcnnjfmnpnmdfa
chrome-extension://mefgmmbdailogpfhfblcnnjfmnpnmdfa/
Those are the Chrome extension IDs for my extension (Feedbro) but you can add the ID for whichever extension you like. The IDs for Chrome extensions can be found by right-click on the extension icon in the toolbar > Manage Extension.