Dillema: we found a lot of subdomains redirected to a lot of non-client’s domains

As title says…

We are preparing a presentation for a client of ours. They're our client for a while (something like two and a half years). Serious money, paycheck on time.

We are with our two projects with them, and they provided a lot with new functionalities and testing.

Now we want to bring them as our SEO client. We made first step, and they said yes. We are preparing a presentation, and noted that their sitemap is in their sister company's url. Which is ok. We will move it to their domain.

But… in those sitemaps we found a lot subdomains. We followed a lead and saw that they're 301 redirected to another client websites of their SEO agency.

Do we want to present that issue as well?

Or just do a proper cleanup if we get a gig?

Any thoughts?