Many samples can be given, let's start with this one, that also has a picture of the huge unexplained (by traditional Sinaiticus science... easy to explain when the ms. is artificially coloured) colour variances.

Parchment Assessment of the Codex Sinaiticus Gavin Moorhead

What can be said with certainty is that any 4th Century parchment with this amount of flexibility, thinness, maker’s holes, repairs and striation is exceptional. It remains indeterminate how these features came to be or how the making process and rigors of history have impacted on the longevity of the parchment.
A nice quote that is better read between the lines. (e.g. The process and rigors of history should not lead to flexibility.)

Interestingly, in our BL correspondence, Gavin, through an administrator, properly called for private study into the colour variance, since the BL lacked time and finances.

So far, we seem to be the only ones doing such study.