Why it matters when you are writing
Writing researchers describe patchwriting as a stage people pass through when working with material they do not yet fully understand. That is a fair description of how it happens and not a defense of the result. If you cannot restate a passage without leaning on its structure, the honest options are to quote it or to keep reading until you can — not to produce a sentence that looks rewritten and is not.
It is easy to spot once you know the shape. Clause order matches the source, the technical terms are identical because they cannot be changed, and the connecting words have been swapped for near-equivalents: “however” for “nevertheless,” “demonstrates” for “shows,” “considerable” for “substantial.” Read your sentence beside the original; if they align phrase for phrase, it is patchwriting regardless of how many words differ.
The fix is mechanical and it works. Close the source. Write what the passage established, in a sentence that starts somewhere else — with the implication, with the population studied, with the comparison. Then reopen the source and check you have not changed the claim. Writers whose first language is not English patchwrite more often, not because of any lack of integrity, but because rebuilding a sentence in a second language is genuinely harder work, and it is worth doing anyway.