Demand for DDR3 is up because people who want DDR5 or DDR4 but can't afford either any more are choosing DDR3 and old DDR3-compatible systems to put it in, instead of what they really want.
At the rate we're going, soon we're going to draw from SIMM stock.
Just to be clear, this was to go into an ancient Dell T420 NUMA system. Well over 10 years old.