THVD1406: There is a peak on the rising edge of the output

These are not spikes. While the THVD1406 is actively driving its outputs (for about 8 µs), the differential output voltage is higher. This is not a problem.

This is likely caused by a combination your RS-485 biasing resistors and other transceivers on the bus. Ultimately, this is not an issue since the differential voltage (VOD=A-B) at your sampling point is what matters. The VOD is still a strong signal.