Best way to clean 4k discs?

[maverick22]

So I picked up the Mulan 2020 4k steelbook at Best Buy. Not only did the steelbook have a few dings, but the disc had 3 scratches at least an inch long.

I exchanged it tonight. The steelbook is in great condition, but this time the disc had milky droplet looking spots all over the laser side of the disc

I tried to wipe it off with my softest t-shirt, but that didn't get most of the spots off. Then I used warm water and dish soap after a quick online search, and then used a microfiber cloth, but that left tons of little micro scratches on the laser side! I can't watch it, but it's "running in the background" while I get some work done at home.

What have you all found is the best/safest method to clean 4k discs?

I can't believe I have to raise this question with brand new discs!

Thanks in advance.