I don't think anyone knows for certain what is going on or why. Many have observed shortened range and longer Supercharging sessions (slower rates and sharper taper) shortly after a Tesla MS battery fire in China and Belgium in May of 2019. Tesla mentioned faster charging times with V2 stalls going from 120kW to 150kW, but many 85kW pack owners noticed both a lower voltage maximum capacity, lower Supercharging speeds, and the taper starts earlier relative to before the software update.
Some have speculated that Tesla feared potential battery fires and decided to restrict the battery capacity and charging rate, while some think Tesla fears being liable for battery replacements under warranty. I'd like to know the truth as it is discovered but I definitely feel out of the loop.