Probably, but it will depend on the interest rate.

The lower the interest rate, the higher the safe level of debt.

Right now federal bonds have a negative interest rate, so perhaps there is no limit to the amount of debt, and in fact that there might be a minimum safe lower bound. Or maybe not; we don't have much experience in dealing with this sort of situation since it was seen to be impossible.

Putting that aside, the UK had debt around 200% of GDP after the Napoleonic Wars, and eventually paid most of it down. So the "bad & unsustainable level" appears to be well above that.