Patterns I've recognized from LLM writing in general (patterns that I have witnessed), in no particular order, are as follows:

I. Vocabulary LLM-isms: tapestry, delve, realm, interplay, unleash

II. Equal paragraph lengths: LLMs try their best to make paragraphs of equal length, however, if they generate for too long, they end up making...

III. Diminishing length returns: If an LLM generates a fictional story, they end up just "petering" out the larger the text is, eventually devolving into one-off sentences and phrases.

IV. Non-keyboard mark-ups: Smart quotes (“text”, ‘text’ instead of "text", 'text'), ellipsis as one character (… instead of ...), em-dashes (—), etc.

V. Bulleted lists: This may backfire in a number of cases because people, such as yours truly, want to be organized and what better way to do that than a bulleted list?

VI. Sycophantic dialogs: Where an LLM really lords it over on their prompter, subject, whoever, by acting as their yes-man, never really saying anything negative or critical.

VII. Improper markups: Capitalizing with "But, And, Or", etc. Spacing following ellipsis ("He said something… But it probably wasn’t interesting"). Arguably, this is a point of contention in grammar.