Imagine that I have ApplicationCritical devices on SwitchA, Vlan 300. SwitchA is connected to Layer3Switch via trunk.
Then NonCriticalApplication devices are connected to SwitchB, Vlan 300. SwitchB is connected to Layer3Switch via trunk.
Devices on SwitchA and SwitchB have no dependency other than sharing same VLAN.
Imagine I need to reboot SwtichB for maintenance.
Do you see how normal STP recalculations generated by the fact I am power cycling SwitchB could affect ApplicationCritical devices functionality on SwitchA? I do not think that is expected, but I am just checking.