Does upgrading from the basic EA access pack to a higher pack cause issues?

Wanted to ask beforehand, don't want to cause an issue with my account as of now. If anyone knows the answer, it'd be appreciated. Also I play on Steam if that's important.

No it won't, in fact its encouraged. You wont have to pay full price, just whatever the difference of the next highest pack is. Also you can link/merge your POE account (which is on the website) and your Steam account that way anything you buy on the website is tied to your Steam account and vice versa. I believe tho the main account details will then be whatever info you use to login on the website (which might be different).

Thank you for the info! It was already linked so worked seamlessly. Thanks again!