For stuff like stadia, which has no real identical products, a transfer would indeed be nicer. But the whole sell of the google domains product is that you are

For stuff like stadia, which has no real identical products, a transfer would indeed be nicer. But the whole sell of the google domains product is that you are getting a domain from Google. If it is no longer from google, the product is largely indistinguishable from those from other large cloud providers like Cloudflare or AWS (or more boutique or focused offerings like Porkbun and Namecheap).