Todays update to kernel 5.14.1-1-next and virtualbox modules cause module failure on reboot.
-- Journal begins at Fri 2021-09-03 11:58:46 BST, ends at Mon 2021-09-06 09:02:26 BST. --
Sep 06 09:01:22 Airtop3 kernel: vboxdrv: version magic '5.14.1-1-next SMP preempt mod_unload modversions RANDSTRUCT_PLUGIN_be4f4640813399b1ea93887b22f49caa0f6e511b4ed75e22e30afdf955b03c9c' should be >
Sep 06 09:01:22 Airtop3 kernel: vboxdrv: version magic '5.14.1-1-next SMP preempt mod_unload modversions RANDSTRUCT_PLUGIN_be4f4640813399b1ea93887b22f49caa0f6e511b4ed75e22e30afdf955b03c9c' should be >
Sep 06 09:01:22 Airtop3 kernel: vboxdrv: version magic '5.14.1-1-next SMP preempt mod_unload modversions RANDSTRUCT_PLUGIN_be4f4640813399b1ea93887b22f49caa0f6e511b4ed75e22e30afdf955b03c9c' should be >
Sep 06 09:01:22 Airtop3 kernel: vboxdrv: version magic '5.14.1-1-next SMP preempt mod_unload modversions RANDSTRUCT_PLUGIN_be4f4640813399b1ea93887b22f49caa0f6e511b4ed75e22e30afdf955b03c9c' should be >
Sep 06 09:01:22 Airtop3 kernel: vboxdrv: version magic '5.14.1-1-next SMP preempt mod_unload modversions RANDSTRUCT_PLUGIN_be4f4640813399b1ea93887b22f49caa0f6e511b4ed75e22e30afdf955b03c9c' should be >
Sep 06 09:01:22 Airtop3 kernel: vboxdrv: version magic '5.14.1-1-next SMP preempt mod_unload modversions RANDSTRUCT_PLUGIN_be4f4640813399b1ea93887b22f49caa0f6e511b4ed75e22e30afdf955b03c9c' should be >
Sep 06 09:01:22 Airtop3 systemd[1]: Failed to start Load Kernel Modules.
Sep 06 09:01:22 Airtop3 systemd-modules-load[315]: Failed to insert module 'vboxnetadp': Exec format error
Sep 06 09:01:22 Airtop3 systemd-modules-load[315]: Failed to insert module 'vboxnetflt': Exec format error
Sep 06 09:01:22 Airtop3 systemd-modules-load[315]: Failed to insert module 'vboxdrv': Exec format error
Sep 06 09:01:22 Airtop3 systemd-modules-load[315]: Failed to insert module 'vboxnetadp': Exec format error
Sep 06 09:01:22 Airtop3 systemd-modules-load[315]: Failed to insert module 'vboxnetflt': Exec format error
Sep 06 09:01:22 Airtop3 systemd-modules-load[315]: Failed to insert module 'vboxdrv': Exec format error
Failure of virtualbox Only.

Rebuild is up, fixes the issue here:

sudo pacman -U http://kaosx.tk/repo/build/virtualbox-modules-next-6.1.26-11-x86_64.pkg.tar.zst

Will move shortly to the apps repo (were I presume you got it from, since it was in [build] since last Friday, it certainly never was in [kde-next]).