Is it a Sigelei Zmax Mini, a
smok Zmax Mini or a knock-off? There is no good reason for the battery to fit snug in the tube. At the worst it's a safety defect because a snug fit could block escape of hot gas if the battery ever vents. You should be able to slide the battery right out of the tube easily with no sticking.
Another possibility is counterfeit
batteries. Maybe it's a rewrap having two layers of plastic shrink tubing.
I use Efest IMR 18350s in my Sigelei Zmax V3 telescopic sometimes and they fit fine.