S2340M, small smudges like bubbles on the screen

Hello,

I routinely clean my Dell monitor with wipes and today I noticed there are smudges on the screen. I thought it was just old dust or dry liquid (such as juice drink splashes). So, I rubbed these spots a few times with alcohol wipes but it didn't come off.

It looks like small bubbles. See attachments.

1) What are they?

2) Should I be concerned if its leaking chemicals?

Can someone help me with this?