Progress Gone

*snip*

A few years ago, my brother and I shared my computer. I bought Battlefield 6 on Steam and accidentally linked it to my brother's EA account. I only realized the connection error when buying EA Play. After relinking to my account (WarsWriter), I logged back into Battlefield 6 on Steam and found my character had reverted to level 1 recruit. How can I recover my character?

(CM: Edited to remove additional language. Please post in the language of the board.)