There’s one point that’s worth making here.
To be fair to YECs, they aren’t the only ones who misrepresent the soft tissue remnants as consisting of unstable original biomolecules when they do not. It’s sadly all too common for the popular scientific press to make the same mistake. Popular science reports aimed at the layman tend to favour clickbait and sensationalism over rigour and factual accuracy, and they very often operate according to the principle of “never let the truth get in the way of a good story.” And with dinosaur soft tissue, what better story is there than the idea that Jurassic Park might some day become a reality?
This being the case, it is essential to go back to the original peer-reviewed literature in order to find out exactly what scientists have and have not discovered. Unfortunately even then it is all too easy to misunderstand things, especially if you are not all that familiar with the terminology involved or aren’t reading things carefully. For example, “heme molecules” or “heme breakdown products” can all too easily be mistaken for “haemoglobin” because the names sound similar, but they are very different things, and the former is far, far, far, far more stable than the latter. Chemical reactions involving individual components of DNA or proteins can all too easily be mistaken for indicating the presence of DNA or proteins themselves when in actual fact all they reveal is the presence of the breakdown products of DNA or proteins.
This problem is often exacerbated by a tendency in apologetics—especially in YEC apologetics—of approaching scientific reports as an ammunition gathering exercise. When you’re looking for factoids to prove your point, you get all sorts of cognitive biases piling in and the risk of making mistakes, misunderstanding things and quote mining goes through the roof.
For what it’s worth this is a mistake I’ve made myself in the past. When I was at university, I latched onto a remark by one of our lecturers who described cosmology as “the subject where 27\pi^4 is of order one.” I took it to mean that cosmologists didn’t care about accuracy or precision but just tended to hand-wave things, when in actual fact what he was referring to was not accuracy but scale—in cosmology the distances, volumes and timescales you deal with are so massive that the difference between 27\pi^4 and 1 pales into insignificance.