Multiple codes on same day

I'm looking for my first Prius and found a 2021 LE with 30,000 miles. Carfax said it was a rental, but it is listed as Toyota Certified so figured that was a good thing. After the test drive, I went to the information section on the infotainment system and looked at the previous warnings that were stored there. There were multiple warnings all in one day on three different dates. July 26th had about 6 warnings, June 15th had about 6 or 7 and May 17th had about 5. It seemed odd that there would be so many warnings on a single day and they were all pretty much the same. Hybrid system, brake system, transmission, blind spot monitor, I can't remember all of them. When questioned, the salesperson said it was ok because all those had to be fixed before they could sell it and if there are any issues, the warranty will cover them. I asked if he could get proof that they had all been fixed. After "checking" with the service department, he said that the in-depth inspection process that they do can cause the system to think there is an error but it's ok. Later he said the errors can show up when the battery gets disconnected. Needless to say, I walked away. Is he telling the truth? Can disconnecting the battery cause multiple errors on one day? (I'm pretty sure it wasn't their inspection process, or it would happen to all cars...)