Skytrax's system is a joke anyway.

Just took a few minutes to compare SQ with LH. Two airlines that most pax here are quite used to.

How would you rate it yourself?

For F, I'd say both offer a very good product. I wouldn't rate one or the other as better or worse. 5/5 if you ask me for both.

Skytrax rates SQ F as 4.5 and LH as 5

For Business class, I'd say that LH's product is fairly average. 3.5 out of 5. Long haul. Shorthaul LH should get 1.5 out of 5, maximum.
While SQ's offer is pretty much 5 out of 5, both sh and lh, when compared to pretty much every other airline. Sure, give it 4.5 if you like, but it's one of the very best C products in the world.

Not so much for Skytrax. They actually rate both, LH and SQ at 4 points for long haul and 4.5 points of short haul! Go figure!

Premium Economy SQ wins 5 vs. 4.5 on LH - I like LH's premium economy product, and I think it's rating is fair. Never flown SQ Y+, but I suppose it being slightly better is reasonable.

Then on regular Economy, Skytrax thinks LH is pure 5 stars lh and 4 stars sh. Don't know which airline they flew to give that rating, but it couldn't have been Lufti (they're reasonable on lh in Economy, but 5 stars is a complete joke)
SQ, with in my eyes the best Y product in the world lh gets 4.5 stars, and 5 stars sh.

After all, it shows how much a joke Skytrax is. It's P2W, if you want to use a word out of the gaming industry. Pay2Win.