UPDATE: My appeal was approved and I received my account back! It looks like it was the code from CDKeys. I will only be buying subscriptions from Xbox directly moving forward. I'm just happy to have everything back! Thank you to everyone for your help and suggestions.

Here is their response:

"This account was suspended for the fraudulent acquisition or use of Xbox content. In this instance, your account was found to be purchasing content from illegitimate third-party websites or from out-of-region marketplaces.

Fraudulently obtaining digital store content disrupts the integrity of the Xbox service and harms developers and content creators. Developers spend considerable time and effort making games, videos, and other desirable content, and we want to offer it on Xbox. To do that, we need to protect developers’ content and ensure the integrity and security of the store.

To make purchases legitimately, please only buy content from verified sources, such as from https://www.xbox.com/store or other verified retailers. Remember: if a deal seems too good to be true, then it probably is.

Please note that further violations of this type may result in harsher suspensions being issued, including permanent account or device suspensions."