Switched from Builder to Code and Now Relationship Doesn't Show

Better yet, is there a way to make taxonomy query vars in the builder without it parsing the information in PHP with slashes?

Sure. What I'm trying to achieve is related to the support you provided here. Except instead of doing it via PHP code, I want to use the tax_query array inside the Builder UI.

However, when I try to put an array inside of the Query Vars field in the Relationships Builder UI, it "sanitizes" the array with slashes, likely to escape the characters being used. I do not want it to sanitize. Unfortunately, there's no sanitization customization in Relationship Builder UI. So I must resort to registering the relationship via PHP code.

Here's what I'm putting in the builder:
https://imgur.com/a/f9xrQzX

Here's the output:

'field' => [
'query_args' => [
    'tax_query' => '[ \'taxonomy\' => \'service-types\', \'field\' => \'slug\', \'terms\' => \'concentrations\' ]',
],

The problem I am experiencing with this is compatibility with another plugin, Admin Columns Pro. When registering relationships via PHP code, ACP doesn't integrate the relationship properly and therefore does not provide capabilities to do inline editing via an admin column. When doing it via the MB Builder UI, it does, which is why I want the Builder to stop sanitizing my Query Vars in this relationship.