Docker on WSL: Bizarre behavior caused by wslrelay process

Question

I have a Next.js app installed in a Docker container mapped to port 3000. My app stopped working after a power outage, but there were no changes in Git. The errors were non sensical. For instance, a build error because a module could not be found, but I could verify was installed. If I commented out that line I got an error about an undefined ORM relation that I'd added a few days ago, which was definitely defined. It seemed as though an older version of the app was running, but the page was hot reloading when I saved changes to files in the project and changes I made were otherwise reflected.

I restarted my computer several times. I cloned the repo into a new directory and built the containers from there. I factory-reset Docker Desktop. I uninstalled Docker and re-installed it, but the problem persisted.

Finally, I noticed by accident that even with all of the Docker Services halted and the containers, images and volumes deleted, localhost:3000 was still reloading in the browser, with cache disabled.

I entered this in PowerShell to find out what process was was using port 3000.

Get-Process -Id (Get-NetTCPConnection -LocalPort 3000).OwningProcess

The response said wslrelay. I killed the process and re-upped the containers.

taskkill /F /PID 
docker compose up

After this my app worked again. What happened?