This is a drain for a kitchen, not too surprising it drained slowly. This is a pretty easy fix, a few more pipe supports needed
All plumbing needs supports, and depending on the materials, it may be from 2.7 feet to 12. Improper support can create air pockets and clogged drains. It may lead to stress on the pipe and fittings causing leaks on both supply and DWV systems. Poor support can also cause the system to be noisy. ABS is fairly cheap plastic, and needs proper support to create the correct slope.
Proper slope helps to prevent clogging, The minimum velocity in a horizontal drain pipe is 2 feet per second (0.61 m/s). This is called the “scouring velocity.” The velocity is intended to keep solids in suspension.
The proper slope for that 2″ drain is ¼ in. per foot (2%) and any pipe ≥ 3 in. – ⅛ in. per foot (1%).
Plumbing is more complicated than you might think!