Plus the general digital archaeology needed to get a decade old project / branch and get it and the developer tools back into a state where you can compile and test it. Probably hard to get a fix in a few days if its only just been found. That's if a non-safety critical issue on a 10+ year old car that will fix itself in 8 months is considered worthy of fixing.

In more general I suspect car companies are a bit reluctant for self-service updates like that because of the potential to brick something. If the clock problem is just tied to an infotainment display, losing that would just annoy the customer until it got to a dealer. If it for example disabled the instrument cluster, then that's a safety issue and might make the car illegal to drive (depending on local laws). If its at a dealer, a failed update can be fixed directly by the technician (replace part, or use alternative programming method etc.).

Although newer cars (particularly Tesla) are perhaps seem a bit more happy to do things like OTA updates. You really hope they don't take a "build fast and break things" approach to development. And have good self-recovery systems.