No public API in this version
The /api/ routes on this host are the website: jobs, account, and webhooks. They are not a supported integration, they are disallowed in robots.txt, and they can change.
A future API, if it ships, would use the same model rules as the site: no CodeFormer, no SUPIR, no BRIA RMBG. It would not include a watermark stripper.
If you need that contract, write through the contact form and choose the topic that fits. Do not scrape the website routes.