How long does a steam web session last ?

[DocThomus]

Hello,
Someone gained access to my account via phishing, I reacted fast and changed my password. But the session is still active. It's still not logged off on my steam login history
https://help.steampowered.com/en/accountdata/SteamLoginHistory
How long does it last? As i changed my password, the phisher would not be able to relog in, but if his session is still active, he will still have access to my account.
I tried the deauthorized action for steam guard, but it only logs off steam guard, it doesn't logs off someone who is connected via the website.
As i guess, the normal timeout looks to be 1 hour, but what if the session is always active? Will it last forever?

[J4MESOX4D]

You're supposed to deauthorize all other devices, not remove Steam Guard.