No, this isn’t normal. If it doesn’t come off when you try to clean it, get a replacement Arc.

No , it doesn’t come off when I clean 

Hey Yesu,

Only hooked-up the Arc to my SONY XR55X94J TV a couple days ago & am seeing the same issue. Been treating the Arc very carefully & the room temp. has been constantly around 20-21°C since delivery(?)

Have you experienced any detrimental effect on performance? Feels like the Arc sounds less clear, less dynamic & I’m having to increase the volume since I noticed the leaking. Even though the speech enhancement function is activated in the S2 app.

What have your retailer &/or SONOS customer service advised?

Your’s in anticipation.

I returned it to Costco and got new one and that one has similar issue but much less , I am not sure if it affects the sound 

Both of the Arcs I bought at Black Friday from Bestbuy have it.