Random 403 Forbidden errors continue, unfortunately.
I'm not seeing that happen with (or without)
use_archiveofourown_gay:true and user/pass set under [archiveofourown.org]. I couldn't try your exact URL because you didn't include it.
Sadly, I don't know any now more than any other time it's come up:
https://github.com/JimmXinu/FanFicFa...oblematicSites