It's literally in the first sentence of the article you posted. "attorneys for Biden discovered classified documents" and contacted the authorities. How does that mean "got caught"? Your own attorneys can't "catch" you.
" Biden's personal attorney said on January 21 that the Justice Department discovered six items containing classification markings during a consensual search of his home the previous day, some of which dated to his tenure in the Senate; investigators also seized some of Biden's handwritten notes from his vice presidency."
" Biden's personal attorney said on January 21 that the Justice Department discovered six items containing classification markings during a consensual search of his home the previous day, some of which dated to his tenure in the Senate; investigators also seized some of Biden's handwritten notes from his vice presidency."