The .1 refers to arkenfox, and has nothing to do with Firefox's versioning.

This is a point release for ESR users to match the upcoming change in arkenfox moving forward. It changes the arkenfox defaults for sanitizing history and downloads history on close to false. We enable sanitizeOnShutdown (2801) to help prevent 1st party website tracking across sessions. We consider history/downloads, which are not accessible to websites, as orthogonal and exempt these. This is a non-destructive change, i.e users won't lose anything. As always, those wishing differently can add overrides

🟪 issues:

• #1974 discussion
• #2013 PR

🟩 changelog summary

• new
  • // user_pref("browser.display.document_color_use", 1) // inactive, replaces no-longer used browser.display.use_system_colors
• changed (prefs used when migrating
  • user_pref("privacy.clearOnShutdown_v2.historyFormDataAndDownloads", false);
  • user_pref("privacy.clearSiteData.historyFormDataAndDownloads", false);
  • user_pref("privacy.clearHistory.historyFormDataAndDownloads", false);
• changed (prefs used in FF136+)