Currently I'm running Firefox Android 140.0 on Android 15, though this issue has been present for the past two to three years, though it has started to occur more often in the past six months. When browsing Private Tabs, the browser will regularly close all these tabs on its own, unprompted, and show the New Tab page for Private Tabs. This is visualised by a slide left animation, similar to switching between tabs by swiping across the navigation bar. Sometimes, this also occurs when switching apps, even though Firefox is locked to prevent its background task from being killed. Normal tabs are not refreshed. The “Close Tabs” setting is set to ''Never''. The specific websites accessed do not change anything, as they are different each time. Steps to reproduce problem: # Open several (5-10) Private tabs # Browse as normal # After a couple of days, whilst browsing, all Private tabs will close themselves. Alternatively, lock the Firefox app in multitasking view, then switch apps for a minute and then return (this tends to happen at random after a couple of days).