Private Windows will not store anything in the Browser, so History, Persistent Storage (cookies, local or session storage or IndexedDB will not be saved), No favicons, cache, or anything will be stored when you close it, you even get less features because some won’t work in Private mode like Adblocker cosmetics picker, and Playlist, and you can’t access history or anything through it, if you try to do a ctrl+H, you will be asked to close the Private window.
You use Private windows when you don’t want the information stored in any way, it is a total different environment.
You can’t even access your extensions unless you go to extension settings, one by one and specify them to work in Private windows.
Permissions also aren’t shared, if you allow cookies in XY domain in normal windows, it won’t be allowed for it in Private windows, you have to add it to the list of cookies allowed in Private windows and only while a private window is opened, once it is closed, the permission is removed.
You can set some settings through Private windows though, like if you go to
brave://flags you will be able to set them in either mode.
I don’t know why your tabs are disappearing but I mean, maybe you are closing them somehow, I have noticed some features like Save Tabs (a flag) will crash in Private windows, but seems like it works fine in normal windows.
You don’t really lose anything by using Normal windows, you can control the persistent storage not to save data you don’t want, the only thing is you might have to remove elements from history, but that’s it, you can do it in the history page or by using
shift+del in the address bar.
But of course, if something closes a normal window, you can get the tabs back, because it keeps information for session and tabs which is not the same as the History, and it is always recorded, so you can do a ctrl+shift+T and bring stuff back, or use the menu (alt+e) and go to history and get all the ‘windows closed’ with their respective tabs.
So you won’t lose anything in case of some crashing or anything.