I know there are already a few questions like this relating to steam not being able to load a specific 32-bit library, or maybe a few others, but I'm getting something a little bit different, I think:
You are missing the following 32-bit libraries, and Steam may not run: libvideo.so libXtst.so.6 libXrandr.so.2 libgobject-2.0.so.0 libgtk-x11-2.0.so.0 libpulse.so.0 libgdk_pixbuf-2.0.so.0 libicui18n.so
So, earlier today I accidentally tried to start steam without mounting a hard drive where some steam games are installed, and it got hung up trying to launch. I closed steam and mounted the drive, then tried to restart it. It seemed to launch like normal, and proceeded to download steam updates as expected. But right after that was done, this error popped up.
I have tried to look around for some way to fix this and haven't found something that worked for me. This error message has persisted even after removing and reinstalling steam. I might have done this wrong as I'm very new to Linux and Ubuntu (and in the middle of transitioning from Windows 10), but I've also tried using the "sudo apt-get install (all the library names)" in the terminal and it did nothing to get rid of this error. I'm unsure what else I can try to do to fix this on my own...