What happened: The permanent deal includes a club option for the 2029-30 season. Sieb's addition awaits his International Transfer Certificate and P-1 visa.
Why it matters: The move gives LAFC another forward with Bundesliga experience. Sieb has represented Germany from the U-16 through U-21 levels.
By the numbers: Sieb made 62 appearances across two loan seasons with Mainz, scoring five goals with three assists. He previously recorded 17 goals and four assists in 66 appearances for Greuther Fürth.
What to watch: Visa and transfer-certificate clearance will determine when Sieb can join LAFC's matchday squad.