Hi,
same problem here, since quite a while.
It usually happens multiple times after a reboot. At some point it "stabilizes" and runs for days without rebooting, usually until after the next reboot after update.
I observe that often, when it comes up, the mobile network is not available. In Settings -> Network & Internet -> "Calls & SMS" and "SIM" are grayed out. Need multiple manual reboots to get mobile network connectivity back.
Managed to get a reboot while being connected to logcat:
[ 11-23 12:37:43.759 1204: 6569 D/TelephonyManager ]requestModemActivityInfo: Sending result to app: ModemActivityInfo{ mTimestamp=1800241 mSleepTimeMs=1619956 mIdleTimeMs=55758 mActivityStatsTechSpecificInfo=[{mRat=UNKNOWN,mFrequencyRange=UNKNOWN,mTxTimeMs[]=[379, 17, 261, 57, 20],mRxTimeMs=112186}]}
[ 11-23 12:37:43.769 1204: 1540 E/system_server ]Cannot read thread CPU times for PID 1204
[ 11-23 12:37:48.900 834: 834 I/android.hardware.health-service.gs101 ]Recording a sample at time 1805
[ 11-23 12:37:48.910 1: 383 F/hardened_malloc ]fatal allocator error: invalid free within a slab yet to be used
[ 11-23 12:37:48.934 1: 383 F/libc ]Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 383 (init), pid 1 (init)
[ 11-23 12:37:48.997 6621: 6621 E/cutils-trace ]Error opening trace file: No such file or directory (2)
[ 11-23 12:37:49.002 6622: 6622 W/crash_dump64 ]failed to attach to thread 1: Operation not permitted
[ 11-23 12:37:49.002 6622: 6622 E/crash_dump64 ]failed to interrupt 1 to detach: No such process
[ 11-23 12:37:49.002 6622: 6622 W/crash_dump64 ]failed to ptrace interrupt thread 1: No such process
[ 11-23 12:37:49.002 6622: 6622 F/crash_dump64 ]crash_dump.cpp:485] failed to attach to thread 383: Operation not permitted
[ 11-23 12:37:49.005 659: 659 I/tombstoned ]received crash request for pid 383
[ 11-23 12:37:49.005 659: 659 E/tombstoned ]unexpected dump type: kDebuggerdAnyIntercept
[ 11-23 12:37:49.005 659: 659 E/tombstoned ]failed to get crash output for type kDebuggerdAnyIntercept
[ 11-23 12:37:49.006 6622: 6622 E/libc ]failed to read response to DumpRequest packet: No message of desired type
[ 11-23 12:37:49.006 6622: 6622 E/crash_dump64 ]failed to connected to tombstoned to report failure