Here's a sampling of stuff I've semi-recently encountered on Github that all spy on you by default. For some, it's undocumented, for others it's a minor subsection in the docs. (Some of them are source-available not free, I didn't keep track as I collected the URLs.)

https://github.com/zed-industries/zed

https://github.com/microsoft/vscode

https://github.com/keystonejs/keystone

https://github.com/meilisearch/meilisearch

https://github.com/hasura/graphql-engine

https://github.com/manticoresoftware/manticoresearch/

https://github.com/coder/code-server

https://github.com/loft-sh/devpod

https://github.com/quickwit-oss/quickwit

https://github.com/rilldata/rill-developer/

https://github.com/hocus-dev/hocus

https://github.com/firezone/firezone

Here's a write-up of how bad it gets -- it's pretty obnoxious: https://www.roboleary.net/tools/2022/04/20/vscode-telemetry....