rtc.wakeup and PAO wakeup conflict！

[xtbwqtq]

from pyb import LED,RTC,standby,Pin
import time,machine,stm,log

stm.mem32[stm.PWR + stm.PWR_CSR] |= 1 << 8

LED(1).on()
time.sleep(10)
rtc = RTC()
rtc.wakeup(10 * 1000, None)

standby()

Using this code I can wake up PA0, but if it is woken up by rtc.wakeup, the LED will keep flashing, it looks like it is constantly restarting. When I don't use stm.mem32[stm.PWR + stm.PWR_CSR] |= 1 << 8, there will be no problem, but I can't use PA0 to wake up