Damage creep isn't really a thing but burst creep certainly is

Some champions affected by 'damage creep' actually do less damage than they used to, but because it's now more front-loaded than ever it seems like more, because taking 1k damage in ~1.5 seconds is a lot more noticeable than taking 1.4k in 2, factoring in HP regen, any innate healing/defense or from allies, etc.

as a demonstration of what I mean, for older champs whose builds have changed in some way

discouraged from buying , damage no longer back-loaded on landing more AAs than whatever he fits into his rotation+passive proc, pushed harder into his spells = Zed is burstier discouraged from buying crit, now stacks first-hit passives like = Shaco is burstier, DPS suffers

it's not just assassins, either; fighters, marksmen, and tanks are all feeling it. Reworks like is burstier than she was pre-rework with her Q spam, delivers her payload in one sudden combo after she pops her E on you when she used to do (much more) over a DoT. smacks you with his W->Q->R for burst if, depending on his AP, his W didn't kill you already.

new champions? all very bursty. Ornn, Xayah, Camille -- even champions who are meant to be skirmishers, or DPS fillers or front lines, are all dropping fat stacks of damage in very short time frames rather than spread out like it used to be.

You're not necessarily dying faster because damage is overall higher, but you're definitely dying faster because damage is far more concentrated into enormous chunks at either the very beginning or very end of the fight, with less emphasis on more drawn-out gameplay patterns than there was before.