I don't think it's important. It looks like someone just wrapped yellow electrical tape around the transformer. I don't know any reason why it even should be there. Most doorbell transformers do not have it. If you are in a humid environment it may have been an attempt to avoid rust. Those core parts are iron.

Yes - it's not even electrical tape. It's a very thin plastic-type tape. It's completely indoors (in my garage), I should have any issues/safety concerns with it removed?

No, it serves no electrical purpose.

Thanks Ron. I see it's listed on their website with tape. So there's ZERO need for the tape?

If you're concerned, contact NuTone. They're the only ones that can give you a definitive answer.

I'm with Ron. It's probably not important.

I contacted a few electricians and MOST said it was just fine. But, one said it helps heat dissipate. So...does anyone think this could affect the way heat dissipates?

the core of the transformer is a set of iron plates. That tape may protect the outside from moisture. It's NOT a big deal. Not even a small deal.

I agree with weed (and I made that comment before), it might keep the plates from corroding in a moist environment but frankly, I doubt it would make much of a difference. In a marine environment it probably won't help and most other places, it isn't necessary.

"Electrical Insulating tapes are used primarily on small to large coils and capacitors to provide mechanical holding power during the manufacturing process (typically varnish impregnation)"

The point to note here, is that the ends of all the thin laminations are probably not protected from moisture very well if you remove the tape. Moisture can cause rust. I have replaced a lot of transformers because the humming was getting bad enough to bother the homeowners. Most of these have been in a utility room right above the condensate drain for the indoor AC coil. The smallest bit of rust can cause the transformer to humm, and it resonates through the junction box. Some rust spots are almost unnoticeable, but if you can take a razor blade, and remove the rust spot between the laminates, that is wedging them apart, without bending the laminate, you can get the humm / buzzing to stop.

I don't know how much of a difference in non-buzzing lifespan you may get for a transformer with or without the tape, because it would have more to do with the environment. A buzzing transformer is not dangerous, just annoying, and $10 is not that big of a deal for a relatively easy DIY fix many years down the road when the sound gets to the annoying point.