Hello,
Could you please share details for HVD and LVD pin details?

Check the schematic of your board to see where exactly is HV_A routed.
For your S32K3 device (e.g., S32K358 in your AEB project), the core voltage (V11) is generated internally using the high‑voltage input domain VDD_HV_A.
Another observation, resetting not happening if I program core 2 with empty while (1) loop.
Resetting happening only, if there some logic in core 2 (even with LED link).
That is a good point. Do you use NXP evalaution board?
If not, you power supply might not be strong enough to execute task on 2 cores and once second core draw higher current the LVDs will reset micro.
But I expect there will be some HW resource sharing issues which will lead to reset. For example not servicing the SWT for core2, etc...
Still best way is to look at FCCU NCFS registers for faults and RGM FES and DES for reset reasons.
Best regards,
Peter