We need to see exactly what you connected to this chip. Show the schematic. It would also help to provide a link directly to the datasheet of the chip.

Updated, thank you

kellogs‭ Well that's a weird schematic. Why do you have zener diodes where one would expect to see capacitors? Are you running this from some raw battery voltage or something? Also if you have a pull-down on the P MOSFET, it will conduct as default, is this intentional? What are the voltages?

Lundin‭ This is meant to be used on a 12V vehicle. TVS diodes for a bit of protection, gate is pulled down by design. Which voltages aside from the ones in main question ?

kellogs‭ I mean the supply voltages. Placing TVS only makes sense on inputs/outputs, not in the middle of the circuit - everything after the voltage regular is to be regarded as relatively clean. You absolutely do need to have decoupling caps there however, 100nF close to the supply pin of the IC. Also in automotive electronics pull resistors of 100k/1M are unacceptable - way too sensitive to EMI. Use 10k max, 4k7 is also common.

Oh and 600W peak pulse is too weak TVS for automotive, you need 1500W. I don't remember which exact standard that requires this, but I do remember failing EMC testing once for this very reason.

@Lundin I shall add some caps, thank you. Do the resistor values still matter if B, T signal frequencies are in the sub-Hz range ?

kellogs‭ The reason why one should avoid high ohm pull resistors is because RF energy from external spurious emissions (radiated or conducted) will be present and with 5V/1Mohm you only need >5uA to pull the line in the opposite direction. There's a big design difference between low power consumer applications and automotive/industrial overall.

Note, automotive applications can see a "load-dump" pulse of about 80V for a very short time. It is a really harsh electrical environment. I once built a blinking LED using a 2N3906 to switch on when the ignition was off (poor man's fake car alarm.) Worked great for a year or two, then one day, it didn't work anymore. Took it apart, and found the 1A fuse included with it had blown. That was because the 2N3906 (only rated for 40V) had shorted, from some event when the battery was at least over 40V. If a fuse hadn't have been used, it could have meant a car fire, then a garage fire!