Overfilled Prius at the pump. Is this a cause for concern?

My understanding is that there are EVAP system vent tubes attached near the top of the Fuel fill tube . If enough gasoline finds it way into those tubes it can mess up the EVAP system.
If you consider a messed up EVAP system serious than the answer is YES.

 

Serious?
Probably not.
If you zorched your purge or vent valves with gasoline then the "Change Owner" light would probably already be illuminated.
Believe it or not, you are not the first.
You might not even be the last.
Evaporative containment systems have been around for decades and people have been over-filling their cars for decades before that.
What Is An Evaporative Control System?

If your Check Engine light illuminates, just read the codes with an OBD2 or drive to the nearest auto parts house and they will likely as not do it for you. If the resulting code points to an Evap system component and you're smart enough to stay away from ANY dealership with a 7-year-old car then this will be a repair involving a $100 part with about a half hour labour at a relatively honest mechanic.
Maybe 200-300 bucks at the very most.

Some Yoo-Toobe sleuthing might make this a <$100 repair - if anything happens at all.

Good Luck!

 

Might want to ask an honest mechanic about how much it might cost to diagnosis and repair the EVAP system in a 2022 Prius if gas has gotten into the vent tubes.

 

The evaporative emissions system in a Prius is also the on-board refueling vapor recovery (ORVR) system.

Overfilling one time might or might not give you a problem with it, depending on how the dice roll.

If you have an ORVR problem, you'll know it. Future fillups might not allow more than a gallon or two in, or spurt fuel back out the filler neck at you, as in this thread:

Gas Pump does not want to pump gas and spills out gas | PriusChat

If you're unlucky and that starts happening, you will need some repairs.

If you're lucky and the car fills up properly the next few times and there's no check-engine light, you escaped problems; go and sin no more.

 

Your driving school might have mentioned reading the owner's manual.
If you were not provided with one when you bought your car, then Toyota has your back!

This might or might not be useful in the interim.

https://assets.sia.toyota.com/publications/en/om-s/OM47F01U/pdf/OM47F01U.pdf?_gl=1*3brdet*_tmna_ga*MjQ1MjQzODAwLjE3MDg0MjY0Njk.*_tmna_ga_EP43E5EFVZ*MTcwODQyNjQ2OS4xLjEuMTcwODQyNjU5Mi4xMS4wLjA.

Section 4-4 mentions refueling and has all of the usual notes, cautions and warnings.

Caveat: This is a US manual, and the Prius is a 'world car.' There may or may not be differences between the US Spec manual (more likely: The North American Spec) and those from other parts of the world.

 

That is one of the parts of the evap and ORVR systems, yes.

When I was a kid there were still cars around here and there that didn't have such systems. But they've been pretty ubiquitous for a long time now.

 

It was more fun with the Gen2's flexible tank: if you over filled that it could really overflow. But that only happened at a bad pump that missed the fill mark.

 

Air is fairly flexible, with or without a layer of rubber. Filling any tank whose ORVR system is b0rked can be entertaining.

 

That's why I always go to self-service when I fill up the tank. I once was at a full service station and I saw the lady was still pumping gas after it clicked. I told her to stop and she replied: "no, my husband is a mechanic and he'll tell you this is a myth, you can't break your car by overfilling it". I replied: "well if this mechanic believe in such non-sense you can rest assured I won't ever call him if I need to repair my car".