No, not all will rot at the bottom like that. I've had lots of rooted cuttings shipped to me and they didn't look like that. However, I wouldn't panic if one looked like that.

Are you talking about the spot at the top of the photo? If so, my cutting had a similar spot and it turned out v to be rot. Does the spot look like it's getting larger? If so use a clean pin or needle and poke the spot. If clear/yellowish clear liquid comes out it's a spot of rot as the sap should be white. There are plenty of posts on here about what to do should it be rot

I forgot to ask, is the spot soft or mushy? The texture of the limb is a good indicator of rot

It's not my pic. Just found it on the forum. Just wondering if its normal for a cutting to rot and save itself.