There was a class action
There was a class action already started on this issue. It was dismissed with prejudice months ago meaning it can't be refiled before the court. I suspect the reason was because there are two US standards bodies that define how the capacity of a gas tank can be legally described and both agree that the advertised tank capacity includes both reserve and splash area.
A usable 14.5 US gallon area is not valid. Toyota said in the letter announcing this CSP replacement availability that the usable area was more like 9.8 gallons. Don't overfill beyond the auto pump shut off.
I had the fix and the only effect for my car was the auto pump shutoff displays on the fuel gauge as slightly above the F mark. Emotionally satisfying, not really getting any more gas in. Probably 20 fills since the fix. All good.