I woke up today and the system proxy settings had been changed when I never use these settings. How did that happen or how do I find out?

I noticed something was wrong right away because Brave browser could not access the Internet. It told me to check my proxy settings.

Sure enough, printing the environment variables gives the following:ALL_PROXY=socks://127.0.0.1:8888/all_proxy=socks://127.0.0.1:8888/NO_PROXY=localhost,127.0.0.0/8,::1no_proxy=localhost,127.0.0.0/8,::1

In the GUI, there is also HTTP proxy set to port 8080.

Edit: there is nothing listening on 127.0.0.1:8888, but there is a host on the network listening on both ports 8888 and 8080 with Firefox bookmarks pointing at these services.

I'm the only person who has access to the computer.

Coincidentally, I have a tab open in Firefox that talks about socks proxy.