Pretty much was the title says. I thought things were clear enough, or got cleared up as you continue reading.

Is it the difference of reading and listening to an audio book?

tl;dr: i said i would beta read someone's book for them but it's unreadable

so i met this person who was looking for beta readers for her book. sure okay, i'd like to start beta reading some books. for context this is an indie author debuting her novel and she's only 16. i open the pdf and within the first page i see formatting like:

“They are growing stronger”, I voice, breaking the silence as the fog from my words disappears before me. “It’s the fear of their living that pushes them harder” A voice calls beneath a black cloak to my right,

(yes, that last comma is at the end of a sentence. and i have never seen 'voice' be used as a verb in this way?)

there are also runon sentences, such as ones of this effect: The return to the cage I intentionally thrust myself into many years is so deeply tiresome I force myself to pause several times, I rest my ability in an attempt to conserve my energy but as the cold stone entrance comes into view I turn to my surroundings revelling in the feeling of the soft breeze washing over my body once more, I listen to the sound of dancing nature around me and I drown in the scent of freedom for the last time, before glamouring my persona and walking through the hidden entrance.

(what even is 'glamouring my persona'???)

i read a few more pages of the book and they're all of similar vagueness/gramattical errors that are standing out to me as ai or machine translated- i say this because this person mentioned that they are from a non english speaking country; though they can just as easily be writng english as a second language, the wording used is making me think it's ai assisted in one shape or another. not to mention that this person's introduction email was in pretty perfect and concise english which sharply contrasts with what's written above (i.e, i suspect her intro email was ai written)

so my question is: how do i go about this? do i suck it up and finish the book? (note it's 450 pages of this...) is this a normal amount of issues in a beta draft of a novel? do i be honest and tell the author that their work is so full of mistakes that it's genuinely unreadable, and i'd be willing to read it after a couple more rounds of edits/ and i suspect ai usage and am vehemently against ai so i'm not comfortable reading it? or do i just be kind and tell her that i unfortunately don't have time to give her feedback? or something else entirely?

i'm conflicted because i'm doing this for free, and i understand there is the expectation of the work not being perfect because i am beta reading it, but i also feel like it's the the author's job to give their beta readers as pleasant of a reading experience as possible.