hmm, I don’t think that this is expected behavior. It looks similar to an issue from a few days ago:
you might want to initially try updating your flyctl client to the latest version, and destroying the builder, then redeploying the app.
If that doesn’t resolve the issue, then you might also try manually re-deploying the builder to a different region.
At the moment, I would recommend a region besides iad, since there looks to be a networking problem in one of its DCs (Fly.io Status - IAD Network Issue)
In any case, this would entail cloning the current machine on the builder app to a different region (fly machines ls, then fly machines clone --region). After that, you’d want to destroy the original machine and its volume.
If you could send over a screenshot of what you see when visiting debug.fly.dev, that might help us dig into things further