I seemed to remember gp3 being (incrementally) cheaper than gp2... yeah, gp3 is 8 cents per GB-month vs 10 for gp2 in us-east-1. That's actually a reasonably significant price difference, now that I look at it.
There were use cases with gp2 where one would over provision capacity to get IOPS. gp3 let you just dial up IOPS which was much cheaper than over provisioning. This may seem a corner case, but it was moderately common.
Also AWS should cut their prices, well in this environment maybe holding them is a cut....