bleepingcomputer[.]com/news/microsoft/microsoft-september-2026-patch-tuesday-fixes-966-flaws-2-zero-days/
bleepingcomputer[.]com/news/microsoft/windows-11-cumulative-updates-kb5124008-and-kb5122880-released/
bleepingcomputer[.]com/news/microsoft/microsoft-releases-windows-10-kb5122878-extended-security-update/
I have not experienced any problems, but I only updated our main PCs & the laptop since we're getting ready for a move and time was tight. The update caused problems for corporate users breaking VPNs, There were also problems with USB audio & remote desktop, with Microsoft releasing an emergency version of the Patch Tuesday update today to fix things.
bleepingcomputer[.]com/news/microsoft/microsoft-september-updates-break-audio-on-some-windows-pcs/
bleepingcomputer[.]com/news/microsoft/microsoft-releases-emergency-windows-updates-to-fix-rds-failures/
Problems have also been reported regarding Lenovo laptop battery charging -- Windows shows power is disconnected when it not. Note: this may also effect other brands/models, but since there are more Lenovo laptops out there, that might mean more problem reports attracting attention.
neowin[.]net/news/user-finds-why-windows-11-kb5121003-may-automatically-cut-power-on-lenovo-pcs/
And the update may be corrupting the BIOS on some PCs/laptops Neowin reports the problem striking HP hardware, but as above, other makes/models may also be effected.
neowin[.]net/news/windows-11-kb5121003-allegedly-corrupts-bios-leading-to-installation-fails-on-hp-systems/