Beard fade
A beard trimmed shorter towards the sideburns so it blends smoothly into a short haircut.
Also: fade (beard), blended beard
A beard fade is trimmed in steps, shortest at the top of the sideburns and longer towards the jaw and chin, so there is no hard line between hair and beard. It borrows the fade from barbering, a haircut that shortens gradually towards the skin. Fades took off with modern barbershop culture in the 2010s. They need a barber's eye and clippers with several guard lengths.