2018 prius c issue

Hey guys, just wondering if you have any indication of what’s going on. Car has 276,000 miles, absolutely great condition, however lately I’ve noticed the digital battery next to the clock has been going completely full more often. This is my second Prius C, and the green bars would never go all the way full, and when they did, the car would act funny and not run as smooth until the bars dropped backdown a little. Lately too, when I take my foot off the gas from getting up to speed Weather that’s 40 mph, 50 mph etc. the engine reps high and then slowly goes down to normal- in my other Prius that I used to have. It would only do that when it was really hot outside, now this one does it every couple of days.

Just now, battery went full green with bars, engine reving when I take my foot off the gas, AND it’s been about twenty min and the car has not shut off. It has not switched into EV mode even when just sitting, gas engine remains on. I turned it off and back on and EV mode is on just fine now.

so is this an indication that the hybrid battery is going out? it hasn’t been replaced yet. And look at that, just as I turned it off and turned it back on, full green bars again out of no where, and I’m telling you, I’ve been driving these cars forever, and even when the battery is “full” it never goes full green- always has a bar at the top to spare. so just hoping for some help, thanks