I like many others prefer to use tab as an inventory button in games like this. As far as I can tell there is no way to disable or rebind the focus switching within UIs in game from tab which also seems to supersede tab when used as the inventory key. This means that when I open my inventory using tab, I have to either close it with the mouse, or press escape to close it out. Pressing my inventory key a second time simply moves my focus from one inventory element to another.
I would imagine this would be a fairly simple fix. Either having this feature be toggleable in the settings or rebindable would solve this for players like me.
Edit: In the meantime, if anyone else is having this issue, you can copy the following into a blank autohotkey script and it should function without interfering with anything else on your computer. All this does is make it so that when you press Tab while playing VS, your computer thinks you pressed e. Just make sure to run the script before you start playing.
#IfWinActive Vintage Story
Tab::e