P0171 code and fuel gauge went from half to 1 blinking bar instantly

3x after fueling up the gauge does go to full but I get about 200 miles and then it goes from a half tank mark to empty in a blink of an eye and goes right to empty with 1 bar blinking. Again add about 4-5 gallons and all seems good.

I recently had my 2007 Prius in the shop to diagnose why I could only put 4 gallons of gas in my tank with the fuel gauge blinking.

Toyota dealership told me this problem is common. They said the ECU just needs to be reflashed because the bladder has a tendency to shrink and expand with the changing seasons from hot and cold the computer needs a reset to get back to a base line for the amount of fuel gauge you can put in during summer the bladder can finally stretch more. I got it home and this time I got it to get up to about 300 miles and same thing happened just slightly under a half tank this time and then plummeted to 1 bar blinking. And got 6 gallons in it this time.

Just prior to the above the check engine light came on with a p0171 (i reset TDC).

Anyone ever have tis happen or a variety of the above happen?