Need help trying to pass a variable of a related entry
This is how it could look like from Twig point of view. I don't know if the Solespace part is correct

{% set priceBracket = entry.relatedAdoptionLink.one() %}
{% set priceUrl = priceBracket !== null? priceBracket.getUrl() : '' %}

{{ form.renderTag({returnUrl: priceURL}) }}