Input inserts U+200C character automatically on : (colon) key

I've had Ubuntu GNOME 16.04 xenial for a while and I've had recently upgraded using -d to Bionic. I'm currently using my old GNOME‌ environment still.

The problem is that whenever I hit the : key, a hidden U+200C unicode character is inserted. This happens in different IDEs and editors including PyCharm and VisualStudio Code. This is very annoying...

What can I do about it?

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