Hi Satake,
The NTB0101 utilizes a one-shot pulse generator to control the operation of the high-side FETs. It generates a brief pulse that turns on the high-side FET. This allows for bidirectional signal translation during this time. After the one-shot pulse operation, the high-side FET turns off and the translation circuit is in a high-impedance state. This means that the A and B sides are effectively disconnected from each other, allowing signals to be isolated.
There should not be any oscillation in the NTB0101. The NTB0101 is designed to work as a level shifter, not as a voltage regulator or signal conditioner.
BR, Tomas