The Superhero Database Classification number, or SHDB Class, is a number that represents the overall 'power' of a character. All traits of a character are used for calculating the Classification.
What it DOESN'T mean
This doesn't mean that a higher class would always beat a lower class character. But the bigger the difference in Class is, the more obvious it is who'll win in a fight.
How is this calculated
( INT^1.3 + (STR*0.5 )^2 + (SPE*0.5)^2 + DUR^1.6 + (POW + (SPS*SPL))^2 + COM^1.8 ) ^ TIER
Super Power Score and Level
Every Super Power has a score (SPS) that is used to calculate the Class. Each Super Power also has 3 levels (SPL). The level is set when connecting that Super Power to a character. The level determines the final score, of the Super Power, being used in the calculation.
And most people who aren't in particular biased against DKD would therefore rightfully scale TLOI to 1-S or to similar boundless tiers in any other wiki.
And if the short version for all the evidence which I posted which easily proves 1-S for DKD still isn't enough for the notorious DKD downplayers,, there's also a very long and detailled versions which proves the same = DKD is 1-S, and in no way inferior even to SCP God tier.