Comment 19 for bug 1983180

Ok, so I've removed the timestamps from the 2 dmesg logs attached by Paulo Marcos and then ran a diff -u, after that I edited out some (non-relevant) memory-address differences and did a second diff -u, this results in this:

--- dmesg_5.10.38-1-lts 2021-06-03 16:29:41.372922210 +0200
+++ dmesg_linux-5.12.5-arch1-1 2021-06-03 16:30:01.013031634 +0200
@@ -92,7 +92,7 @@
 ACPI: IRQ9 used by override.
 Using ACPI (MADT) for SMP configuration information
 ACPI: HPET id: 0x8086a201 base: 0xfed00000
-ACPI: Core revision 20200925
+ACPI: Core revision 20210105
 PM: Registering ACPI NVS region [mem 0x7156c000-0x7156cfff] (4096 bytes)
 PM: Registering ACPI NVS region [mem 0x8a88f000-0x8af7efff] (7274496 bytes)
 ACPI FADT declares the system doesn't support PCIe ASPM, so disable it
@@ -113,10 +113,6 @@
 ACPI: Dynamic OEM Table Load:
 ACPI: SSDT 0xFFFF... 0003FF (v02 PmRef Cpu0Cst 00003001 INTL 20160527)
 ACPI: Dynamic OEM Table Load:
-ACPI: SSDT 0xFFFF... 0000BA (v02 PmRef Cpu0Hwp 00003000 INTL 20160527)
-ACPI: Dynamic OEM Table Load:
-ACPI: SSDT 0xFFFF... 000628 (v02 PmRef HwpLvt 00003000 INTL 20160527)
-ACPI: Dynamic OEM Table Load:
 ACPI: SSDT 0xFFFF... 000D14 (v02 PmRef ApIst 00003000 INTL 20160527)
 ACPI: Dynamic OEM Table Load:
 ACPI: SSDT 0xFFFF... 000317 (v02 PmRef ApHwp 00003000 INTL 20160527)

(there are other differences later during boots, but these are the ones which count).

So for some reason the kernel is no longer loading the Cpu0Hwp and HwpLvt SSDT-s, and that is causing these errors.