Residential proxies are controversial, as the majority of them are made available via adware inserted into mobile apps, running without the device owner's knowledge about it:

Residential proxy networks grow through several mechanisms. The most widespread is SDK-based provisioning: proxy companies pay mobile developers to embed their SDK into free or low-cost applications, which ships with a lengthy end-user licence agreement that, buried in legal language, consents to routing third-party traffic through the user's device. Most users click through without reading it (Trend Micro, 2025; Google, 2026; FBI, 2026).

https://www.first.org/blog/20260424-Infrastructure-Nobody-Owns