How can I type quotation marks directly without hitting space in different app? Every time I want to use ", ', or ` I have to hit space to type a single character. In some apps, for example VS Code, this situation is worse where I cannot even type a single character. Here is a gif that shows what I mean:

https://i.imgur.com/GJE42BO.gif

So how can I disable this? I am using an external USB Keyboard with ANSI Layout. I am currently still on Mojave since I have to wait for updates on a few apps before switching to Catalina.
Go to System Preferences > Keyboard > Input Sources and get rid of the item called "US International PC".  Instead use US or ABC.

(US International PC is a special layout where those characters are deadkeys for typing accent marks used is various European languages).