To split hairs, "low carb" means different things to different groups of people. Lifelong adherents of the keto diet put the limit at around 20g of carbs per day. But you can find research studies and the like where they take a normal Western diet (75-90% carbs) and reduce it to say, 60% carbs and then refer to THAT as "low carb."

It's not splitting hairs. Unless you are extremely physically active, even ~100g of carbs a day will inhibit ketosis where the liver converts fats into ketones for powering your brain and body. This is easily seen by using ketone strips to detect ketones in urine.