Steam Categories under "My Games"

A family member has their Steam account under the same Windows account as me, which means their installed games show up in my library and vice versa (for reasons I cannot fathom). It appears there is no setting to turn this off.

I can get around this by going to Library > My Games, which only shows my personal games. However, this makes my categories disappear! In a large library, this makes browsing my own games difficult (especially as I'm not done retagging since Steam recently deleted all my categories o_o).

So my question is this:

How do I display my library without others' libraries showing up and with the categories intact?

Making a second Windows account is technically probably a solution, but would be rather inconvenient and should be unnecessary.

Others have recommended third party tools for organizing libraries (e.g. here); perhaps it can be done there but this seems like a trivial feature to have built-in. Another potential option I suppose is to move the install location of all their games (e.g. like this)? But this seems failure prone and manual labor heavy.

This is a limitation based on the fact you're both logged into and have games installed to the same Steam installation. If you use separate OS-level user accounts that should fix it because you would each then have your own Steam installation, etc.

It may also be fixed by at least one of y'all moving your games to a "Steam Library Folder" outside of the default folder, but it doesn't seem like it based on what you've said and how the client is known to behave.

All that being said, yeah it does seem like it should still show categories when viewing "My Games" in a multi-user installation, and you could try contacting support but it's unlikely to get fixed reasonably soon unless there's some public outcry.