Looks like frost damage, or perhaps it got hit by an herbicide or herbicide drift from a nearby garden. First year irises are particularly susceptible to such stresses. Don't worry, though. It should bloom normally next year unless it gets hit with another late freeze or herbicide then.

Laurie

Wow! I had one, out a few hundred in my beds do that same thing this year. It is really strange! I wonder if I hit it with the weed and feed or something.
Hazienmoon

It can be genetic . I used to collect them ;my goal was to cross them with a large bloom strain that could not be supported by the stem . but I lost my land before I could accomplish this .

Thanks, everyone. I did use some Round Up in a somewhat nearby area. Should I remove the scape before that lower bud blooms or just leave it?

Just leave it. It won't hurt anything.

Just leaving it may result in a collection of moisture down among the leaves. Personally i would remove it. If the lower bud is showing colour, you could pop it in a tiny vase and enjoy the bloom inside. I say this because when mine do this, it is usually frosty weather that causes it, and there are few other blooms in the garden then, so every bloom is precious.

I had the same thing here this year on one plant. I've had this iris bed for 10 years & this is a first for me. The other several hundred irises are fine, though.....