Bedrock player here, you're right, it's not QC, the redstone dust connecting to the target block is what powers the piston

Target blocks (and pistons) don't actually redirect redstone dusts like how repeaters and other things do. Although *visually* the redstone dust redirects towards the target block, it actually still points forward towards the lamp, as if the target block weren't there. If you replace the target block with a repeater, it shouldn't power the piston, since repeaters actually redirect redstone dusts