Some internal services are only reachable through a corporate SOCKS5 proxy. On a laptop, you handle that with a PAC file. On iOS you can't: there's no per-app proxy configuration, and most apps ignore the system proxy anyway.
Source: [Dev.to](https://dev.to/michbsd/transparent-socks5-access-from-ios-with-a-tailscale-app-connector-and-sing-box-2fhd)