MacPro6,1 can't stay in Stop after upgrading Sequoia and Safari.

As per title, Moved from Sequoia 15.7.4 to 15.7.5 and from Safari 26.3 to 26.4.

Anyone else experienced the same? How to resolve?

Tried already to remove and reinstall the patches, install them a second time, reset the Mac by unplugging the power cord for 15+ sec, messed around with Energy parameters and also changed FeatureUnlock from Partial to Disabled. Tried also to switch the monitor off straight after putting in Stop, and even before. Nothing really helped.

My current config: CPU 4-cores, D300, SSD OWC 2TB, 64 GB RAM, Cinema Display HD 30". No changes here pre-/post-OS upgrade.

Thanks in advance for your help!