You can interact with redstone powered blocks inside of spawn protection by powering them outside of spawn protection.

Steps to Reproduce:

• Start a server and join it
• Give operator permissions to yourself
• Set the world spawn to your current location and find the edge
• Place a dispenser right next to the border of the spawn protection and fill it with arrows
• Place a button right outside spawn protection and next to the dispenser
• Remove operator permissions from yourself
• Give operator permissions to a different player
• Power the dispenser by using the button located outside spawn protection

The dispenser is triggered and the arrow is fired, despite it being inside of spawn protection.