I only found 2 contributions on this topic. Both are titled in a very non-explicit manner ("Log out" and "Timeout"). Thus I am creating this more explicit topic.

I have been using Protonmail and Protondrive for several years.

I keep being flabbergasted by the fact that you persist in not filling this glaring security hole. As if you never heard the saying "the (security) error lies between the chair and the keyboard".

There SHOULD be a feature that enables the user to set a default (custom) timeout duration, so that the session ends after the specified amount of time, if not closed by the user.

Being forced to manually close the session oneself as the sole means to know the session will end sometime is blatantly insufficient and cumbersome.

PLEASE address this security problem. Security is not only technical, it also consists of empowering users to have a more secure use of tools.