I would say it's bad practice because you end up having to copy all the build dependencies (source code) to the host and you're potentially putting a bunch of extra load on the host during the build process.

Also adds moving parts to your deploy which increases risk/introduces more failure modes.

Couple things that come to mind

- disk space exhaustion during build

- I/o exhaustion esp with package managers that have lots of small files (npm)

However, on the small/hobby end I don't think it's a huge concern.