Some low flow models are created so that you just press it to run enough water to down a piss, but hold it to unleash all the stored water to down anything more. That was the point of them, save water by fixing the obvious problem of downing a tank of water over a little urine. But unless you bought the toilet or were told, you don’t know that, and that’s where a lot of the issue comes from. Same interface as any other, different expected input and results.

On the other hand, I once had an old toilet that did require multiple flushes. It was not a low flow, and there was nothing wrong with the toilet. Years of accumulation had restricted the plumbing like 30 feet down. Plumber eventually sorted that out.