SUMMARY
***
Plasmashell crashes when trying to add addon/plasmoid and appmenu bar is set up. I rechecked this with a fresh KDE installation on a VM (Endeavour). Same there.
***


STEPS TO REPRODUCE
1. install a fresh kde/plasma or update to the latest
2. create a new taskbar (app taskbar on top of screen)
3. try to add another addon/plasmoid (Miniprogramm in German)

OBSERVED RESULT
After 3-4 seconds screen gets black, plasmashell crashes and reloads. Removing the top application bar and logout/login. Plasmoids can be added again until I add the application menubar in top.

EXPECTED RESULT
should show dialog left hand side to add plasmoid from selection.

SOFTWARE/OS VERSIONS
Operating System: EndeavourOS
KDE Plasma Version: 5.25.5
KDE Frameworks Version: 5.97.0
Qt Version: 5.15.5
Kernel Version: 5.15.65-1-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 RENOIR
Manufacturer: LENOVO
Product Name: 20UES00L00
System Version: ThinkPad T14 Gen 1


Beginning of log in "journalctl -xe" after crash:

Sep 08 19:43:16 t14 plasmashell[11380]: Could not find the Plasmoid for Plasma::FrameSvgItem(0x55c7803fab40) QQmlContext(0x7fa058006220) QUrl("file:/>
Sep 08 19:43:16 t14 plasmashell[11380]: Could not find the Plasmoid for Plasma::FrameSvgItem(0x55c7803fab40) QQmlContext(0x7fa058006220) QUrl("file:/>
Sep 08 19:43:16 t14 plasmashell[11380]: file:///usr/lib/qt/qml/org/kde/plasma/extras/PlaceholderMessage.qml:238:5: QML Heading: Binding loop detected>
Sep 08 19:43:17 t14 audit[11380]: ANOM_ABEND auid=1000 uid=1000 gid=1000 ses=2 pid=11380 comm="plasmashell" exe="/usr/bin/plasmashell" sig=11 res=1
Sep 08 19:43:17 t14 kernel: plasmashell[11380]: segfault at 7ffc03300ff8 ip 00007fa06a547655 sp 00007ffc03301000 error 6 in libQt5Core.so.5.15.5[7fa0>
Sep 08 19:43:17 t14 kernel: Code: 8d 50 18 41 5c 48 0f 45 c2 c3 0f 1f 00 48 8d 56 10 48 81 fa ff ff ff 7f 0f 87 87 00 00 00 48 89 fe 48 89 df 40 f6 c>
Sep 08 19:43:17 t14 kernel: audit: type=1701 audit(1662658997.735:401): auid=1000 uid=1000 gid=1000 ses=2 pid=11380 comm="plasmashell" exe="/usr/bin/>
Sep 08 19:43:17 t14 kernel: audit: type=1334 audit(1662658997.745:402): prog-id=50 op=LOAD
Sep 08 19:43:17 t14 kernel: audit: type=1334 audit(1662658997.745:403): prog-id=51 op=LOAD
Sep 08 19:43:17 t14 kernel: audit: type=1334 audit(1662658997.745:404): prog-id=52 op=LOAD
Sep 08 19:43:17 t14 kernel: audit: type=1130 audit(1662658997.755:405): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-coredump@3-13918>
Sep 08 19:43:17 t14 audit: BPF prog-id=50 op=LOAD
Sep 08 19:43:17 t14 audit: BPF prog-id=51 op=LOAD
Sep 08 19:43:17 t14 audit: BPF prog-id=52 op=LOAD
Sep 08 19:43:17 t14 audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-coredump@3-13918-0 comm="systemd" exe="/usr/>
Sep 08 19:43:17 t14 systemd[1]: Started Process Core Dump (PID 13918/UID 0).
░░ Subject: A start job for unit systemd-coredump@3-13918-0.service has finished successfully
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ A start job for unit systemd-coredump@3-13918-0.service has finished successfully.
░░ 
░░ The job identifier is 3072.
Sep 08 19:43:19 t14 systemd-coredump[13919]: [🡕] Process 11380 (plasmashell) of user 1000 dumped core.