To answer the original poster’s question.
The article I read stated that this was nothing more than a test. The current Cup race car was designed to accommodate an EV power plant if the NASCAR racing community ever chooses to go in that direction. The article also stated that NASCAR officials watched a race in Japan with hydrogen powered cars as they were guests of Toyota. Toyota appears to be a big proponent of using hydrogen to power cars instead of batteries.
Lastly, NASCAR officials in this article clearly stated that they have no intention of moving away from the internal combustion engine for the foreseeable future. Yes, one can argue that the foreseeable future is a relative term; however, team owners at all three levels of NASCAR are struggling with costs. This includes some of the big teams. It will be very expensive to move to this technology, and overnight make all of their drivetrain equipment obsolete. This includes the equipment they use to build and test the drivetrains.