If there was a PAC URL set and the server that hosts the PAC was not reachable, OCSP requests would have been blocked, resulting in incorrect error pages being shown. This vulnerability affects Firefox < 102, Firefox ESR < 91.11, Thunderbird < 102, and Thunderbird < 91.11.
https://www.mozilla.org/security/advisories/mfsa2022-26/
https://www.mozilla.org/security/advisories/mfsa2022-25/