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It flickers when I move the mouse in the lower right corner (area 1 by 1 inch), right above the XFCE panel or in twm .
It is OK in Manjaro or Windows.
$ uname -a
Linux dell-5500 6.5.4-arch2-1 #1 SMP PREEMPT_DYNAMIC Thu, 21 Sep 2023 11:06:39 +0000 x86_64 GNU/Linux
$ lspci
00:02.0 VGA compatible controller: Intel Corporation WhiskeyLake-U GT2 [UHD Graphics 620] (rev 02) (prog-if 00 [VGA controller])
DeviceName: Onboard - Video
Subsystem: Dell WhiskeyLake-U GT2 [UHD Graphics 620]
Flags: bus master, fast devsel, latency 0, IRQ 136, IOMMU group 0
Memory at 90000000 (64-bit, non-prefetchable) [size=16M]
Memory at 80000000 (64-bit, prefetchable) [size=256M]
I/O ports at 3000 [size=64]
Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
Capabilities: <access denied>
Kernel driver in use: i915
Kernel modules: i915$ journalctl
Sep 24 12:32:00 dell-5500 kernel: Command line: BOOT_IMAGE=/boot/vmlinuz-linux root=UUID=6e8720a9-ba79-416c-8499-91cb668d7877 rw audit=0 sysrq_always_enabled=1 intel_iommu=on kfence.sample_interval=100 mitigations=off i915.mitigations=off loglevel=3 quiet
Sep 24 12:32:00 dell-5500 kernel: Kernel command line: BOOT_IMAGE=/boot/vmlinuz-linux root=UUID=6e8720a9-ba79-416c-8499-91cb668d7877 rw audit=0 sysrq_always_enabled=1 intel_iommu=on kfence.sample_interval=100 mitigations=off i915.mitigations=off loglevel=3 quiet
Sep 24 12:32:00 dell-5500 kernel: ACPI: bus type drm_connector registered
Sep 24 12:32:00 dell-5500 kernel: [drm] Initialized simpledrm 1.0.0 20200625 for simple-framebuffer.0 on minor 0
Sep 24 12:32:00 dell-5500 kernel: simple-framebuffer simple-framebuffer.0: [drm] fb0: simpledrmdrmfb frame buffer device
Sep 24 12:32:00 dell-5500 kernel: i915 0000:00:02.0: [drm] VT-d active for gfx access
Sep 24 12:32:00 dell-5500 kernel: i915 0000:00:02.0: vgaarb: deactivate vga console
Sep 24 12:32:00 dell-5500 kernel: i915 0000:00:02.0: [drm] Using Transparent Hugepages
Sep 24 12:32:00 dell-5500 kernel: i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem
Sep 24 12:32:00 dell-5500 kernel: i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/kbl_dmc_ver1_04.bin (v1.4)
Sep 24 12:32:00 dell-5500 kernel: i915 0000:00:02.0: [drm] [ENCODER:102:DDI B/PHY B] is disabled/in DSI mode with an ungated DDI clock, gate it
Sep 24 12:32:00 dell-5500 kernel: i915 0000:00:02.0: [drm] [ENCODER:111:DDI C/PHY C] is disabled/in DSI mode with an ungated DDI clock, gate it
Sep 24 12:32:00 dell-5500 kernel: [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 1
Sep 24 12:32:00 dell-5500 kernel: fbcon: i915drmfb (fb0) is primary device
Sep 24 12:32:00 dell-5500 kernel: i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device
Sep 24 12:32:00 dell-5500 systemd[1]: Starting Load Kernel Module drm...
Sep 24 12:32:02 dell-5500 kernel: mei_hdcp 0000:00:16.0-b638ab7e-94e2-4ea2-a552-d1c54b627f04: bound 0000:00:02.0 (ops i915_hdcp_ops [i915])
Sep 24 12:32:02 dell-5500 kernel: snd_hda_intel 0000:00:1f.3: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])
Sep 24 12:34:35 dell-5500 kernel: i915 0000:00:02.0: [drm] *ERROR* CPU pipe A FIFO underrunOffline