There's no difference between anyone's API keys. They all hit the hit the same API and return the same data.

What's the request(s) you're making on the API?

I'm using it on a video addon and his API key pulls up great quality artwork images but mine is showing lesser quality. Not sure if I entered the key incorrectly or what. Any ideas?

I'm sorry I'm not sure what you're asking lol so i hope i answered your question

What do you mean by requests? Sorry I'm not very tech savvy lol

An API Request is the request that is sent to TMDb, requesting data and information about a movie.
It's something like this:

https://api.themoviedb.org/3/discover/movie?api_key=[MY_KEY]&year=1971&page=1&include_video=false&sort_by=original_title.asc&region=BR&language=pt-PT

Your Addon is the one who is building, writing this requisition.
Writing based on rules pre-established by him.
And also probably because of the options you've made in his settings.
And finally, for the request you made: movie title, serials, actor name, etc ...
Your Addon considers all of this and creates an API Request.

You probably will not be able to see this Requisition, so you will not be able to paste here.
And without knowing what the request was made, hardly anyone here from TMDb will be able to help.
The best place to find help is with the creator of this Addon.
If it's a Kodi Addon, for example, there should be a topic on the Kodi forum about this Addon.
And you're probably not the only one with this problem. And maybe the solution is there.

In any case, enter here, the name of the Addon, in which program it is installed.
And what is the operating system: Windows, OSX, Android, etc ...
Maybe someone here, who uses this Addon, can give some help.

Okay that makes a bit more sense lol. The addon is Placenta and the program im assuming is Kodi? Im operating on an Android device (Nvidia Shield)

Thank you for your help.