Cookies don't clear bug while tab still open
The Delete Browsing Data option, manually or by the quit button, doesn't clear cookies if the tab is still open.
Simple example: go to youtube.com, search for anything, e.g. "asmr". In the same tab, go to a new site, e g. google.com. Then go to settings and Delete Browsing Data, with all selected but downloads. Now, all tabs are closed, so in a new tab go to youtube.com, and click in the search and the previous search, e.g. "asmr", shows up in a droplist.
This droplist behavior shouldn't occur when all data is cleared. This behavior doesn't occur if the tab is closed before Delete Browsing History is selected.
If you're experiencing a bug where cookies are not cleared in Firefox for Android while a tab is still open, you can try the following steps to resolve the issue:
Update Firefox: Make sure you have the latest version of Firefox installed on your Android device. Open the Google Play Store, go to the "My apps & games" section, and check if an update is available for Firefox. If an update is available, install it and see if the issue persists.
Restart Firefox: Close all tabs in Firefox and exit the app. Then, relaunch Firefox and check if the cookies are clearing properly. Restarting the app can help resolve temporary issues.
Clear cookies manually: If the bug persists, you can try manually clearing the cookies from within Firefox. Open Firefox, tap the menu button (three vertical dots), go to "Settings," and then select "Privacy." Tap on "Clear private data" and make sure the "Cookies & active logins" option is selected. Tap "Clear data" to remove the cookies. Note that this will also log you out of any websites where you were previously logged in.