Ubuntu 26.04 Random reboots on my laptop

For a couple weeks now, I've been experiencing random reboots on my laptop.

They happen once or twice a day or not at all, either while in use (black screen), from suspend, or at boot (-> GRUB-menu). All I do at the laptop is write texts and ocassionally game.

From my logs, these "Previous system reset reason" messages jump out at me:

• internal CPU shutdown event occured - Coincides with reboot times, except at boot.
• software wrote 0x6 to reset control register 0xCF9 - Too many, but a few coincide with at boot.
• ACPI power state transition occurred - Rare, possibly unrelated.

See sample logs HERE and HERE. (Some things are redacted.) Also, see my CPU information HERE.

Architecture:                x86_64
  CPU op-mode(s):            32-bit, 64-bit
  Address sizes:             44 bits physical, 48 bits virtual
  Byte Order:                Little Endian
CPU(s):                      8
  On-line CPU(s) list:       0-7
Vendor ID:                   AuthenticAMD
  Model name:                AMD Ryzen 3 7320U with Radeon Graphics
    CPU family:              23
    Model:                   160
    Thread(s) per core:      2
    Core(s) per socket:      4
    Socket(s):               1
    Stepping:                0
    Frequency boost:         enabled
    CPU(s) scaling MHz:      37%
    CPU max MHz:             4151.7300
    CPU min MHz:             425.1780
    BogoMIPS:                4791.29
    Flags:                   fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pg
                             e mca cmov pat pse36 clflush mmx fxsr sse sse2 ht s
                             yscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constan
                             t_tsc rep_good nopl xtopology nonstop_tsc cpuid ext
                             d_apicid aperfmperf rapl pni pclmulqdq monitor ssse
                             3 fma cx16 sse4_1 sse4_2 x2apic movbe popcnt aes xs
                             ave avx f16c rdrand lahf_lm cmp_legacy svm extapic 
                             cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw
                              ibs skinit wdt tce topoext perfctr_core perfctr_nb
                              bpext perfctr_llc mwaitx cpb cat_l3 cdp_l3 hw_psta
                             te ssbd mba ibrs ibpb stibp vmmcall fsgsbase bmi1 a
                             vx2 smep bmi2 cqm rdt_a rdseed adx smap clflushopt 
                             clwb sha_ni xsaveopt xsavec xgetbv1 cqm_llc cqm_occ
                             up_llc cqm_mbm_total cqm_mbm_local clzero irperf xs
                             aveerptr rdpru wbnoinvd cppc arat npt lbrv svm_lock
                              nrip_save tsc_scale vmcb_clean flushbyasid decodea
                             ssists pausefilter pfthreshold avic v_vmsave_vmload
                              vgif v_spec_ctrl umip rdpid overflow_recov succor 
                             smca sev sev_es
Virtualization features:     
  Virtualization:            AMD-V
Caches (sum of all):         
  L1d:                       128 KiB (4 instances)
  L1i:                       128 KiB (4 instances)
  L2:                        2 MiB (4 instances)
  L3:                        4 MiB (1 instance)
NUMA:                        
  NUMA node(s):              1
  NUMA node0 CPU(s):         0-7
Vulnerabilities:             
  Gather data sampling:      Not affected
  Ghostwrite:                Not affected
  Indirect target selection: Not affected
  Itlb multihit:             Not affected
  L1tf:                      Not affected
  Mds:                       Not affected
  Meltdown:                  Not affected
  Mmio stale data:           Not affected
  Old microcode:             Not affected
  Reg file data sampling:    Not affected
  Retbleed:                  Mitigation; untrained return thunk; SMT enabled wit
                             h STIBP protection
  Spec rstack overflow:      Mitigation; Safe RET
  Spec store bypass:         Mitigation; Speculative Store Bypass disabled via p
                             rctl
  Spectre v1:                Mitigation; usercopy/swapgs barriers and __user poi
                             nter sanitization
  Spectre v2:                Mitigation; Retpolines; IBPB conditional; STIBP alw
                             ays-on; RSB filling; PBRSB-eIBRS Not affected; BHI 
                             Not affected
  Srbds:                     Not affected
  Tsa:                       Not affected
  Tsx async abort:           Not affected
  Vmscape:                   Mitigation; IBPB before exit to userspace

Since upgrading to Ubuntu 26.04, I've had Linux kernel panics at boot once in a blue moon. Could this be relevant?

The only software I've installed within these last few weeks are VSCodium and .NET SDK.

For VSCodium:

1. snap install codium --classic
2. "Getting all telemetry out"
3. Installed muhammadsammy's C# plugin through VSCodium
4. Installed .NET SDK (see later)
5. Uninstall everything (wasn't happy)
   • Including sudo rm /usr/local/bin/dotnet (again, see later)

For .NET SDK:

1. sudo snap install dotnet-sdk --classic (or dotnet-sdk-100 when installing VSCodium)
2. sudo ln -s /snap/dotnet-sdk/current/dotnet /usr/local/bin/dotnet (for dot-net-100)
3. Added to ~.profile:
   • export DOTNET_CLI_TELEMETRY_OPTOUT=true
   • export DOTNET_ROOT=/snap/dotnet-sdk/current

What I've tried:

• Disabling Fast Boot, makes no difference?
• Running MyAsus System Diagnostics, all OK
• Keeping tabs on systemctl timers, not correlated

What I haven't tried:

• Running memtest
• Fresh reinstall
• Changing other BIOS/UEFI settings

Update 1: BIOS update

As suggested by ChanganAuto, I updated the BIOS. As it turns out, I was on version 306 (2023/07/25). I followed the instructions from both "BIOS Update" and my laptop vendor's:

1. Back up my stuff plus /boot/efi/EFI
2. Download the latest BIOS for my device (BIOS for ASUS EZ Flash Utility Version 318)
3. Unzip the file, then move its content to /boot/efi/EFI
4. Use ASUS Firmware Update from ASUS in UEFI on the file

Will update if the issue still persists.

Update 2: It Gets Worse

The problem is still present, perhaps worse. I had 3 reboots this morning. Oddly enough, I had none yesterday. See today's boot logs: 08:33, 08:56, 09:55, 10:28.