v128, now. Deleted prefs.js, opened FF, reset all my settings, restarted firefox, and the Home > New Windows and Tabs settings both reset themselves to "Blank Page". In the new prefs.js, "browser.startup.homepage" is still set to my homepage, it just isn't being used because the parent is set to "Blank Page". The "General > Tabs > Open links in tabs instead of new windows" setting also got reset to unchecked. However, changes to "Home > Firefox Home Content" were preserved, as well as everything I changed under "Search" and "Privacy & Security". For extensions, I have only a password manager and ublock installed.