SUMMARY
***
When Global Menu is used I can't open Google Chrome Browser in incognito mode. 
When a regular Chrome session is running, too, it works. When NO Chrome instance is running and I try to open an incognito session it immediately closes the window. Removing Global Menu form the task bar makes Chrome behaving normally.

Starting Chrome from the CLI gives me this output:

[p@endeavour ~]$ google-chrome-stable --incognito
Gtk-Message: 09:29:36.030: Failed to load module "appmenu-gtk-module"
[4178:4178:0827/092936.222592:ERROR:object_proxy.cc(590)] Failed to call method: org.freedesktop.portal.Settings.Read: object_path= /org/freedesktop/portal/desktop: org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.portal.Desktop was not provided by any .service files
libva error: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
[0827/092936.285972:ERROR:elf_dynamic_array_reader.h(64)] tag not found
[0827/092936.286108:ERROR:elf_dynamic_array_reader.h(64)] tag not found
[4221:4221:0827/092936.286818:ERROR:viz_main_impl.cc(186)] Exiting GPU process due to errors during initialization
[0827/092936.301891:ERROR:file_io_posix.cc(144)] open /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq: No such file or directory (2)
[0827/092936.301942:ERROR:file_io_posix.cc(144)] open /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq: No such file or directory (2)
[4222:4242:0827/092937.752054:ERROR:ssl_client_socket_impl.cc(980)] handshake failed; returned -1, SSL error code 1, net_error -3
58789512802560:error:1000007d:SSL routines:OPENSSL_internal:CERTIFICATE_VERIFY_FAILED:../../third_party/boringssl/src/ssl/handshake.cc:393:
[4222:4242:0827/092937.753066:ERROR:ssl_client_socket_impl.cc(980)] handshake failed; returned -1, SSL error code 1, net_error -3
[4222:4242:0827/092937.753650:ERROR:ssl_client_socket_impl.cc(980)] handshake failed; returned -1, SSL error code 1, net_error -3
Speicherzugriffsfehler (Speicherabzug geschrieben)




For reference and sorting out misleadingerrors/outputs here's the working regular Chrome instance outpit:
[p@endeavour ~]$ google-chrome-stable
Gtk-Message: 09:31:16.005: Failed to load module "appmenu-gtk-module"
[4703:4703:0827/093116.204104:ERROR:object_proxy.cc(590)] Failed to call method: org.freedesktop.portal.Settings.Read: object_path= /org/freedesktop/portal/desktop: org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.portal.Desktop was not provided by any .service files
libva error: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
[4745:4745:0827/093116.242048:ERROR:viz_main_impl.cc(186)] Exiting GPU process due to errors during initialization
libva error: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
[4838:4838:0827/093116.461744:ERROR:viz_main_impl.cc(186)] Exiting GPU process due to errors during initialization
libva error: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
[4855:11:0827/093116.543728:ERROR:command_buffer_proxy_impl.cc(128)] ContextResult::kTransientFailure: Failed to send GpuControl.CreateCommandBuffer.
[4792:9:0827/093116.549958:ERROR:command_buffer_proxy_impl.cc(128)] ContextResult::kTransientFailure: Failed to send GpuControl.CreateCommandBuffer.
[4907:4907:0827/093116.617726:ERROR:gl_utils.cc(402)] [.WebGL-0x26bc00873100]GL Driver Message (OpenGL, Performance, GL_CLOSE_PATH_NV, High): GPU stall due to ReadPixels
[4907:4907:0827/093116.726065:ERROR:gl_utils.cc(402)] [.WebGL-0x26bc00873100]GL Driver Message (OpenGL, Performance, GL_CLOSE_PATH_NV, High): GPU stall due to ReadPixels
[4907:4907:0827/093116.786121:ERROR:gl_utils.cc(402)] [.WebGL-0x26bc00873100]GL Driver Message (OpenGL, Performance, GL_CLOSE_PATH_NV, High): GPU stall due to ReadPixels
[4703:4703:0827/093118.416648:ERROR:feature_processor_state.cc(39)] Processing error occured: model WebAppInstallationPromo failed with UkmEngineDisabled, message: 
***


STEPS TO REPRODUCE
1.  activate Global Menu in any taskbar
2.  start Google Chrome as only Chrome instance in incognito mode

OBSERVED RESULT
Window frame opens and closes immediately

EXPECTED RESULT
Chrome should start in incognito mode

SOFTWARE/OS VERSIONS
Operating System: EndeavourOS 
KDE Plasma Version: 5.27.7
KDE Frameworks Version: 5.109.0
Qt Version: 5.15.10
Kernel Version: 6.1.47-1-lts (64-bit)
Graphics Platform: X11
Processors: 16 × AMD Ryzen 7 PRO 4750U with Radeon Graphics
Memory: 30.6 GiB of RAM
Graphics Processor: AMD Radeon Graphics
Manufacturer: LENOVO
Product Name: 20UES00L00
System Version: ThinkPad T14 Gen 1