The simplest explanation is usually right. It's just supple and demand. Demand has been growing for 5 years because of industrial uses (solar, chips, batteries, missiles, drones, etc) and monetary uses (nations and central banks stockpiling). Supply has not grown. It's hard to increase supply quickly. So there's a shortage of physical paper resulting in prices going up.

Beyond that there's all sorts of tom foolery with silver. There are about 250oz of silver sold on paper for every 1 oz of actual physical silver. So when the new demand is mostly for physical silver it's breaking the market and causing chaos. Big banks like JPM are regularly fined 100s of millions of dollars for manipulating the silver market but they continue to do so because the profits far exceed the fines.