You cannot compare a text value with a post object field. A post object field holds only the ID of the post object. The title of the post object is part of that other post and not part of the relationship field.
Their is nothing built into WP that will let you do this in a single query.
You would first need to search the posts of the other post type to get the ID based on the text. Then you can use the ID value(s) returned by this first query in your second query.
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