Valve contractor Timothee Besset commented on GitHub to say it's 'Today's beta update comes with a fairly significant change to the way we setup the runtime environment for the web views.
Valve are hot on the issue though and they've already put up a fresh Steam Beta with a fix. So what can you do? Well, if you're comfortable with your package managing you could downgrade freetype2 back to version 2.10.4 but that can then end up breaking future updates that depend on the newer version. This is obviously a big problem and makes it all quite unusable. When loading any part of the Steam client that depends on web views, it will just give you a rather unhelpful black screen.
If you're using Arch Linux or anything based on it (or other rolling update distributions) and you've recently run updates that included freetype2, you might unfortunately notice that Steam is now quite broken.
