2021 Prius Prime charging time change 5+hrs to 11+hrs

8 Amps should charge a Gen 4 in 8 hours. That's more like 6 Amps.

 

Yep, check your systems settings. Previous owner must've backed it down to 8A max charging rate. I'm usually at less than 1% when I get home, and it gets a full charge in less than 4.25 hours on the factory 110VAC charging cable.
Also make sure the time & DATE is set correctly on your car. The dealership inputted the wrong date into my car; so my charging schedule was off a few days every week. I'm setup on a scheduled timed charge to take advantage of my utility's discounted power usage. This also prevents me from popping circuit breakers, since all my appliances are usually off during those times.
Now if your talking about the estimated charge time to full; that'll vary wildly. It's dependent on battery temperature and weather you answered yes or no to using the AC unit to cool down the battery during charging. The system is programmed to protect the traction battery pack, so it's not going to pump 12A into the pack if it's too hot and will step down the charging amperage to keep from destroying the pack. That's why your seeing the wild charging times.
I've installed window visors on my car and keep the windows down about 1/4 inch. The battery cooling air is removed from the car's passenger compartment - so run your AC if it's too warm. Your traction battery will thank you, with a long life....

Hope this helps.....