I noticed the latest gitpod container uses npm 8 and node 16 which are not supported for BJS builds. So when trying to launch a new gitpod workspace which can take a long time there is eventually an error while building node-sass.
Downgrading to node 6 and node 14 with
$ npm install -g npm@6 $ nvm install 14
from the gitpod terminal seems to fix then running
$ npm install $ npm start
to complete the setup.
Perhaps it would be possible to configure gitpod to use an older container ?