should be:
>Although 80% of the content was my own writing, the fact that it was run through an LLM engine for grammar and vocabulary cross-checking meant that it failed the "probably written by AI" metric, and it was rejected.
1. 80 % -> 80%
2. in -> through
3. a LLM -> an LLM
4. enginee -> engine
5. cross-check -> cross-checking
6. cross-checking, -> cross-checking (removed the comma)
7. made it failed -> meant that it failed, (or "made it fail" depending on whether you want to preserve the past tense or preserve the word "made")
8. probable -> probably
9. by AI " -> by AI"
10. ; and it was -> , and it was (no need for a semicolon when linking with a conjunction like "and", and I would consider another word or phrase such as ", and, as a result, it was rejected" to emphasize the causal relationship between the clauses)
Relying on AI for editing seems to have atrophied the author's writing if that is what he or she thinks is worth publishing on a blog like this. I would suggest practicing editing your own work and not even thinking about passing it through AI (especially when you were told not to use any AI!) to edit for a while. Given that English is not your first (or even second or third) language, I would also suggest having a native speaker with some demonstrable writing skill review your writing and give feedback on how to make it more idiomatic. For example, writing being "run through an LLM" rather than "run in an LLM" is a relatively subtle difference compared to the others, and it's very very common for preposition mistakes like this to show up when writing in another language than your first. I am still hopeless with French prepositions.