"The proxy server is refusing connections" after Tor has bootstrapped

Sometimes Tor Browser shows "The proxy server is refusing connections" after Tor has bootstrapped successfully. In the analysis below (#20297 (comment 234055)) 1.7% of all test suite runs were affected, and no reason was found why it should be test suite specific so this might be a real issue affecting users.

The last journal entry with identifiers "Tor" or "tor" from an affected test run [1]:

Mar 22 22:48:21 amnesia Tor[8620]: Bootstrapped 100% (done): Done
[...]
Mar 22 22:48:37 amnesia onion-grater[4388]: 10.200.1.2:45186 (filter: tor-browser) connected: loaded filter: tor-browser
Mar 22 22:48:38 amnesia Tor[8620]: New control connection opened from 127.0.0.1.

I couldn't find anything else relevant in the journal.

Failed test suite runs:

• [1] https://jenkins.tails.boum.org/job/test_Tails_ISO_20277-extend-apparmor-regex/2//cucumber-html-reports/report-feature_35_1732831431.html (screenshot, journal, debug.log)