What added ". $HOME/.limbo/env" to my ~/.profile?

After about 3 weeks, I rebooted my Ubuntu 22.04 LTS system. Upon login, I got an error dialog.

My ~/.profile had this new line near the end:

. $HOME/.limbo/env

I didn’t add this myself.

I had installed GHC (Glasgow Haskell Compiler) recently, and its setup added a line after this one, so whatever added .limbo/env must have done so before GHC.

I've searched online but found nothing.

There is no ~/.limbo directory on my system. I have searched my logs for any hints, checked the integrity of my packages, looked for rootkits, ... but everything came up empty.

To be honest, I do not remember everything I installed/updated on my system. It was mostly installs/updates from Ubuntu repos (like sudo apt-get install heaptrack), a cargo install hyperfine, and GHC installation with curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | sh. And maybe something I do not remember and cannot find ...

Has anyone else seen this or know what could be behind it?