Values for t4 extra fields

Where are the values for t4 extra fields stored? They are obviously not where Joomla keeps its core extra fields values.

Edit:

I found this in the content in the attribs column

Issue I'm facing is when I put formatted text in editor extra field I run into

0 Error decoding JSON data: Syntax error

Any help?

May I know which extra fields are you referring to? as by default in T4 Blank template, there is no extra field like that.

You can share the credentials of your site eg: URL, Admin + FTP account so I can check for you.