What is Bus capacitance in I2C? How it limits number of devices can be connected to the bus?
You need at least 2 time constants of risetime, given the passive pullup. Otherwise the positive-going waveform will not reach a clean "high" and the data-sampling circuits will conclude a "0" was transmitted.

Thus for 1Kohm pullup and 500 pF total capacitane (wiring, PCB, the ICs hanging on the buss with ESD protection and their data-sampling circuits), you have 500 nanoseconds time constant, and since you need at least 2 tau settling (with that being quite marginal), the bittime must be at least as long as 2 * 500nS = 1,000nS = 1uS => 1MHz rate.

I imagine Philipps has conservative specs on their IP. Respect that.