Switching language bug

Hello! I wonder if anyone else is having the same issue.

I just bought this computer and upgraded the system to OS Catalina. Since I didn't actually have time to use the laptop while it was still on Mojave I don't know whether it's an OS bug or something is wrong with this laptop.

The thing is, I frequently change between Russian and Spanish. Now, when I change the input language (⌘ + ␣), there are three possible results:

1) the flag on the toolbar changes so does the language;

2) the flag on the toolbat changes, but the language doesn't;

3) the flag doesn't change, but the language does.

I also noticed that sometimes the language changes out of the blue. I'm literally just typing a message, without using any shortcuts, and the language just switches.

Has anyone had this? Do you know how to solve this?

Thanks!