Prepping concrete floor for laminate
Each flooring manufacturer has specific guidelines for the amount of tolerance for their product. It varies, but it is usually something like 1/8" (2 mm+/-), using a 4' or 8' straightedge. If your condition is a little drop, not a gradual difference, I would grind it down to make the transition over a larger area, say 1-2 ft out, or get a little thinset and fill it a bit.