This seems to be especially true for official. I've played some vanilla community servers and they seem to be better. So it might be server performance related?

I agree. I made a gigantic jump in debug that left me red flashing. After recovering to full health and hit a concrete road edge, and died. Its one of the reasons I made the issue.

Similar thing with the road flare. Also tabbing out of the game and tabbing back in will remove the sound.

Same issue happening to me. No problems on 1.29

I think it has to do with shifting gears while starting the bike. At least thats when it happens to me.

I don't understand why earplugs aren't a thing on official, especially since there is no disadvantage to other players.

And yes, that is my prefered solution. But tuning them down to an normal noise level would also work.