Something I’ve been wondering. Could it be that the bell that is intended to slip over the top of this is actually intended to slip down and seal on the outside of the flange, rather than on the 21” pipe itself? In that case, it doesn’t matter if the cut on the pipe is erratic, only that the bell is deep enough to fit over it.
That would make sense, it might be that if they did not initially plan on doing that that they will switch to it in order to ensure that the seal works even though the cut was somewhat disappointing. I did hear they had several kinds of seals in order to accommodate various degrees of smoothness in the cut, in addition to trying to smooth it out with the saw. So there are some preparations being made, the question, as usual, is if it is enough.