I too would like to know what the fault is
You say this has Piezo Injectors, a quick Look a AD Online confirms that. However, on your trace I see Injector Voltage peaking at 9v. Something not quite right there ?? I'm thinking that's a set up issue, are you using an attenuator ??
Because all is well before and after the glitch for hours I'm thinking that the driver possibly may not notice the fault, Is it throwing a fault code and illuminating the Engine Light ?? Do you have fault codes ? What are they ?
Answers to the above questions would be a great help to fill the gaps.
Based on what I have seen I would, for now, Guess at Injector Piezo Stack Shorting to Earth internally, Possibly Wiring, then ECU needing a re Flow in that order.
If that was in front of me I would be doing an Insulation / Capacitance test to Injector Body / Ground on the injector & wiring using a Bosch FSA 050 or Megger MIT 420 / 480 tester shooting up to 200v (recommended is 100v) into it.
The Alternative is to swap that injector with another to see if the fault moves. Then you will know if it is the Injector or Wiring / ECU.
Granted, if it takes 2 hours plus to see the fault then you will be working for Love not Money.