Assert the id of the Webflow site that published the page, from data-wf-site. It proves a scenario runs against the site it was written for (production, staging or a copy). The id is in Webflow's Site settings, under General.
Examples
Then this should be the webflow site "6a282ca3f318327eefc29a02"
Then this page should be the webflow site "6a906778b7eda4ebf3917813"
And this should be the webflow site "69d62bbcbf9a56f0284fdb53"
Then this page should be the webflow site "webflow-steps-demo"
And this should be the webflow site "6a083ff5f8d83bda5c5b3e15"
Pattern
Then(/^this( page)? should be the webflow site "([^"]*)"$/, …)
Part of @webship-js/webflow-steps (github.com/webship/webflow-steps), a step pack for Webship-js 2.0.x.