Android compilation splits into multiple dex files even though method limit is not hit

I'm trying to avoid having a multidex app, as it has a hit on app start time. I am pretty close to the border, but under it. However, I still get a classes.dex and classes2.dex files. When I analyse the resulting APK in android studio I see:

The total is 64295 references methods, under the 64k limit of 65536 references methods. Why is it creating 2 dex files and requiring me to add multidex support? Is there any way to solve this?

Using Adobe Air SDK 28