While Hrishikesh may be able to tell what is going on with your repo, our usual debugging guidance is to help you debug.
Something I would suggest you try before he is back (this is his weekend as he works Weds-Sun), is this portion of our site build debugging support guide:
In it, I talk about how to ensure that Netlify is using the same versions of all of the software that you are, since it is frequently the case that a different version of node, npm, yarn, etc can create vastly (or subtly) different build output that can be pretty hard to debug.
Could you run through those steps for us in the meantime, to ensure that our versions match what you use locally to create a correct build?