Weird sound only when clutch engaged and throttle applied

I have started to notice this weird sound on 2025 Scrambler 400x that only happens when clutch is engaged and I'm adding throttle, as soon as I pull clutch or go off the throttle it's completely gone. It sounds like "ts-ts-ts-ts-ts-ts", almost like I would expect to brake pads to slightly rub against the brake disc (obviously it's not that but I would expect it to sound something like that). And the frequency is increasing with amount of throttle added. I can best hear it when riding in 3+ gear. It's coming somewhere from the engine area I would say, so not from the back of the bike.
I tried to make a video to record it but it's very hard because of the wind and the sound is not very loud.
Wondering if anyone has any clues what could it be? I did clean and lube the chain, checked tension, cleaned front sprocket area, no difference.