Using Alt+Shift to change input language opens "File" menu on linux

I use Alt+Shift keyboad combination to change input languages. On my Linux (Xubuntu 18.04) pressing Alt+Shift results in the Joplin “File” menu being open in addition to changing the input language. As a result I have to press [Alt+Shift], [Esc] every time to continue the input.

I think it’s an Electron issue, I’ve seen this behavior in other Electron apps (Wire, YakYak, RocketChat -

Is there a way to have an option to disable this behavior?