Thanks for the report. I cannot reproduce anymore on current master.
Crash is already fixed by rB3cef9ebaf810: Fix T97356: Crash when adding adjustment layer strip
Please download and test latest 3.2 build from buildbot: https://builder.blender.org/download/daily
Feel free to comment if you can still replicate crash.

The crash is still there in blender-3.2.0-alpha+master.179100c02126-windows.amd64-release

I added a video demonstrating the crash on 179100c02126

https://youtu.be/YR_a8uQv1es

Bump!

The current definition of SEQ_get_channels_by_seq is broken, it doesn't return channels. I think the idea was to do this instead:

ListBase *SEQ_get_channels_by_seq(ListBase *seqbase, ListBase *channels, const Sequence *seq)
{
  ListBase *lb = NULL;

  LISTBASE_FOREACH (Sequence *, iseq, seqbase) {
    if (seq == iseq) {
      return channels;
    }
    if ((lb = SEQ_get_channels_by_seq(&iseq->seqbase, &iseq->channels, seq))) {
      return lb;
    }
  }

  return NULL;
}

This code works for me when tested against the steps which crash the VSE.

Called as:

...
ListBase *channels = SEQ_get_channels_by_seq(&ed->seqbase, &ed->channels, seq);
...

@a (blenderbug12345) Thanks for snippet, your code is correct. I was confused for a bit before I noticed pointer to seqbase is being returned.