Projects have a limit of 128MB of space on the container (though as you’ve seen, things written to ‘/tmp’ don’t count towards that). If possible, you want to see if you can remove any dependencies, move static assets to the separate assets storage (which has a further 512MB) and clear out any old git objects from .git
My app has no large static assets. It’s all code and NPM dependencies that’s taking up space. Think I would be fine with just a bit more space, another 25M would probably be enough with some headroom.