Firstly, Spider ID? Also possible relation to ~100+ serious bite reactions in past 1-2yrs
It is a wolf spider. It grows from about 1cm to 5cm long. Wolf spiders are usually gray with brown to dark gray markings. It does not spin webs, instead it actively hunts it's prey. Wolf spiders are agile, robust and have excellent eyesight$^1$. That is why you have noticed that it is quite aware of your movements.
Hogna radiata:

Alopecosa Kochi:

The bite of this spider leaves prominent marks$^2$.

In severe cases, the surrounding area may develop redness, swelling, and even ulcers that spread beyond just the bite location. Allergic reactions may cause even more severe symptoms in some people$^2$.

Since the wolf spider is not poisonous its bite can be treated by cleaning the area with soap and water and then placing a bandage over it$^2$.
Note:
I am unable to identify the exact genus of the spider. I believe it could be Hogna or Alopecia. Someone more knowledgeable could inform me.
References:
1.Wikepedia
2.Healthline