Maybe I'm very lenient about grammar and punctuation mistakes because I don't speak English and English can be confusing even with spell check and grammatical correction shortcut Plus, some puctuations are used differently accross languages ( Such as " and ' for direct speech between American and British English).
Unless that shit is paid (like published book or premium novel), I usually won't make a fuss about it, or even drop it. The creator between the free content might be not an English speaker, or can't hire a proofreader or pay for grammar correction service. It is also harder for non-native speakers to proofread by themselves, as they're sometimes insensitive to the mistake.
As long as I can still understand what's going on, the mistake isn't too stupid or fatal (like "they're" and "their"), and the story is interesting enough, I won't drop or refuse to read a novel because a petty grammatical error; especially the free one sure I'd perhaps feel annoyed, but dropping a novel because of it it's too far. The most reason I drop a novel are the plot, the theme, and the characters which are the main pillars of a story; not technical trivialities.
A person said to me: "Why you write novel in English when you can barely write it correctly?" and maybe some of you thought so when seeing people try to write in rather broken English. People have different reasons; for me it's because I want to learn English, and I find the international readers more open-minded to some topics and less judgmental
Also no, I'm not justifying myself or being defensive; I just wanna present another point of view. If you find grammatical mistakes on my work feel free to point them off, and if you feel dropping or for any reason feel free to even better if you can tell me what can be improved
Just my unimportant two cents though