In the Firefox 152 onwards there is a setting under Privacy and security > History. This option is, “Never remember history”. If this is enabled then every subsequent instance of Firefox henceforth launched will be a private/incognito instance. Typically this means that all the site settings will be cleared and/or add-ons/extensions will be disabled typically.
An alternative to disable history entirely in Firefox, if that is required, is to navigate to Privacy and security > History, enable the option, “Customize history”. Then click on “Choose what you want firefox to remember”. In the Advanced settings enable only the “Clear history when Firefox closes” and disable the other 3 options, namely “Always use private browsing mode”, “Remember browsing and download history”, “Remember search and form history”. Finally below “Clear history when Firefox closes”, click on Settings and enable what is required to be deleted.
For those of you who want to get their hands dirty, well there is another way to disable the Never remember history. That is go to about:config in Firefox new tab and look for the key browser.privatebrowsing.autostart. Change the value to false and restart. This method is not recommended. Just fun to know.