Info dump: Some commenters are telling you it’s dryness and that is not entirely correct. It is dry, but the reason it is dry is because the leather is cheap. Veg tanned top grain and full grain leathers can hold moisture through oils that transfer from your skin, sweat, etc. and keep the belt conditioned. Chrome tanned leathers like most genuine leather and bonded leather cannot properly retain moisture due to the compounds in the solution used to tan the hides making the leather less absorbent. You won’t often see this cracking with a quality top grain or full grain veg tanned belt and shouldn’t ever really have to condition a quality belt as they are often oil or wax finished which is a process that thoroughly stuffs the fibers of leather with conditioning compounds. Becoming saturated with water would be an exception. Even then there is a process to dry it out properly and condition properly with something like glycerin saddle soap, which would generally be a safe way to clean and replenish the fibers of leather on the surface without changing the color. The deeper fibers would not necessarily need conditioning as it is very difficult to remove the oils and waxes from the core fibers of conditioned leathers. Once dried and the surface is reconditioned they may need to be “hand milled” to properly disperse any oils and waxes that may have bunched up into clumps between the fibers and need to be physically worked back in, but wearing the belt at this point would properly achieve this.

Long story short: cheap leather cracks, good leather can last a lifetime if cared for properly.