I'm a bit confused about the thesis requirements. Generally, I see 80,000 but a lot of them claim to for Humanities but STEM course to roughly around 35,000 - 45,000 words?

Is there anyone here who submitted a thesis with this word limit?

I'm doing a Computer Science PhD, my thesis is roughly 43,000 words and 135 pages.

My department has a 50,000 word limit excluding references, tables etc. However, unofficially know one checks unless it is massively over. So I would just submit it and hope people ignore it.

Check your uni guidelines and look at other people thesis who have passed out within your department. Your supervisor should be able to inform you also.
Remember its quality over quantity