Where does a custom-built practice management/client portal tool actually get hosted, and what's involved in maintaining it long-term?

The custom client portal tool currently runs on Supabase and Vercel, with the underlying hosting managed by the contractor building it; the firm owner wasn't fully sure of the technical details of where it lives. The eventual plan is to move it to the firm's own server (mentioned as possibly Microsoft or AWS), though the specifics of what that migration and ongoing maintenance would require were still unclear to the speaker. This ties into the plan to hire an offshore senior software engineer who could set up a proper sandbox environment and handle hosting/maintenance going forward.