Sanitizer.sys.mjd indeed retries the clear on startup if it failed on shutdown, and to do that it uses the pending pref to extract the last pending sanitization. It looks like this was not handled correctly, indeed multiple code points still use PREF_SHUTDOWN_BRANCH, but the new dialog moved to a different pref branch: https://searchfox.org/mozilla-central/rev/54a5c4f14f3eb514a29e0cebcb5a095144bcd450/browser/modules/Sanitizer.sys.mjs#178,185,346,352,363
Bug 1907783 Comment 3 Edit History
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Sanitizer.sys.mjs indeed retries the clear on startup if it failed on shutdown, and to do that it uses the pending pref to extract the last pending sanitization. It looks like this was not handled correctly, indeed multiple code points still use PREF_SHUTDOWN_BRANCH, but the new dialog moved to a different pref branch: https://searchfox.org/mozilla-central/rev/54a5c4f14f3eb514a29e0cebcb5a095144bcd450/browser/modules/Sanitizer.sys.mjs#178,185,346,352,363