Your broad hnmr peak out at 8.2 is almost certainly the indole NH.

It's broad because it's an exchangeable proton.

There are several ways to prove this.

You could put a small drop of D2O in the nmr tube, shake, then re-run the sample.  You should see almost complete disappearance of the signal.

Another method is to run the sample in CD3OD, rather than CDCl3. Again, it should almost totally disappear.

Another method is to run the sample at a higher temp, typically 10 degrees higher.  This will sometimes sharpen the peak, or/and shift the peak.

Nice work.

I always had my money on dmt being less prone to oxidation, compared to what you have shown.