Proxy keeps switching itself back on in Windows

Check the browser side too. If Chrome or Edge has an extension that controls proxy settings (VPN and coupon extensions do this), it keeps rewriting it. Chrome's proxy page tells you outright 'an extension is controlling this setting'. Also worth a look in Task Scheduler for anything odd that runs at login.

Something is turning it back on, so switching it off by hand will never stick. Usual suspects, in the order I'd check them: 1. Work or school laptop? Then it's a group policy and only IT can change it. 2. A VPN, ad blocker or 'privacy' app that routes traffic through itself. Uninstall it and see if the setting stays off. 3. Adware. Fake proxies are a classic way to hijack browsing, so run a proper malware scan. Also check the 'Use setup script' toggle on the same Proxy page, people turn off the manual proxy and miss that one. And in an admin command prompt, netsh winhttp show proxy tells you if there's a system-level proxy set separately. netsh winhttp reset proxy clears it.