I wouldn't say that was me, although I have decades of fault finding computing & electronics components.
I disagree, my view is that the problem lies within the connectors specifically the white connector in this excellent write up of the problem and solution. If you look at the phyisical location it is right next to the floor heating duct. I am in South Australia where for 9 months of the year it is warm and heating is rarely used, however for the remainder it is cold (4-14 deg C) and this is when my problem got a lot worse. It was present during the warmer months but very intermittent and almost non-existent. When the heater got used in anger it would only be 5 minutes into a drive that Car Play would disconnect, followed by cursing at Hyundai with four letter words!
I contacted Hyundai however they were no help, just told me they needed to do a software update but couldn't since the system was down (for weeks mind you!). I gave up and thought I would give this a thread fix a go.
Illustrated guide to replacing Carplay/Android USB port
I failed to disconnect the blue connector, however I wasn't as concerned since this is housed within the head unit and doubt that the connection is poor or impacted too much by heat due to its location. I did wiggle it a bit though.
The white connector is very easy to get to, mounted right on the heating duct! I applied "Conductive Carbon Grease"
Conductive Carbon Grease 50g | Jaycar Electronics as others have within this thread and it has been stable since.
My conclusion based on this is that the connectors in the white plug expand rapidly from a cool to a warm state when the heater is working hard. This is causing the 12V feed to the USB port to interminttently disconnect and then reconnect. The conductive grease is providing insulation and a better connection hence stabilising it, although still far from ideal!
Jitterbug may mask the problem since the disconnect/reconnect may be quite short therefore it may be able to provide enough power to maintain the Car Play during the glitch. (I've not tried & would recommend the carbon grease on the white & blue plugs before it).
If Hyundai are simply replacing the wiring loom without the grease the problem may still be present.
Very happy to hear other theories & be corrected. I am also really disappointed with Hyundai's level of service. It took me to chase this, not them and haven't felt the love! I have also had Tesla's since 2020, with a few issues and they have been excellent (sorry Hyundai, you need to get better in an EV world!)