I can definitively agree on the explanation stated infering the second point. However, it is an aspect which needs further clarification, like op said: “someone else’s skin” is usualy interpreted as human directed (https://dictionary.cambridge.org/dictionary/english/someone). This essentially introduces double meaning within the argument.

In terms of vegetable tanning your best knowledge is correct, it costs more as it requires substantially more time thats why it is only used for higher end or artisan leather. Additionally, I have stated synthetic tanning which is comparable to vegetable, but not as bad as chromium.

& the original person’s comment about chromium-salts looks spot-on, & was ignored by your counter.

In regards to that, can you provide relevant information which details it?

While the conclusion of this argument is valid your premises don’t follow a logical sequence. Firstly, leather is defined as a material obtained from rawhide which is tanned (https://en.wikipedia.org/wiki/Leather) - this is real leather, there is no need for calls to ignorance here.

Secondly, what do mean by referring to “someone else’s”? Because the common usage for such statements usually mean human, not non-human animals. This essentially looks like an emotional appeal at this point.

Thirdly, you state that it is common for leather to be coated in plastic. While this is technically correct - as large portion of the market is composed of reusing scraps, it dismisses leather production from virgin rawhide and processes using vegetable or synthetic tanning which don’t need plastic for the resultant product.