How would you use variables in Trix, if possible?

If we allow our users to add variables inside the Trix field, like this:
```
{{some_variable}}
```
That could map to something like `@user.first_name`

How can we replace the Trix text for example with `.gsub` - on which attribute object should we apply it?

It has been asked here, I had the same `ActionText::RichText` error:
https://stackoverflow.com/questions/65327776/embedding-variable-inside-text-using-trix?noredirect=1#comment129433161_65327776