Oh boy, more enshittification
Amazon pricing seems heavily weighted on whether you shopped around online or not. I think they have tracking cookies that check whether or not your comparing prices. If you do, they keep their prices reasonable, if not, they slowly jack them up until you start, then they back off a bit.
See that’s the wacky thing for the mower specifically. Not only do I shop with a browser that has all cookies disabled, I must have checked on the price for the mower ten times over many months along with some alternatives and even other websites. I think they inflate the price if it’s a 3rd party vendor selling on Amazon sometimes.