How would you go about specifying a text filter that is used in a ‘NOT IN’ filter in Metabase?
I would try a Field filter, if possible, using a NOT() (or anything similar to it in your database) around it.
Other than that, for instance, in MySQL, you could go for functions like FIND_IN_SET, and input your string as a list of items comma-separated. Not ideal, but possible (given your database has some function along those lines).
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