I recently lost everything in skyblock to a death trap that utilized fall damage. I had a level 99 harvest hoe, and some really good armor, and some other things on me, and none of them were retrieved from the trapper because I did not have a video recording of it. To prevent these death traps, I think it would be reasonable for players to not take fall damage whilst on other players islands. the amount of times iv died and lost things on other islands, sometimes not to death traps is immense. this is especially a hazard for rookies as rookies don't have the ability to retrieve their items most of the time when they die to fall damage on anther players island. [if you are seeing this please try to get it do the developers so they can see this and do their best to fix it.]
This sounds like a good idea! I have not played Skyblock in a while, so I can't comment too much on how it'll affect gameplay and stuff like that. That said, being cautious about where you go and storing items/important goods beforehand is the best method of prevention because people will obviously find other ways to build deathtraps, so I'm not sure if this idea will help too much. Hopefully someone who mains Skyblock can offer their two cents. I'm neutral for now.
I'd say make it so it negates dying at all in other islands because a lot of deathtraps also use lava and other ways and not only fall; the problem with that is that will make people cry that /god is now not really useful and that is why it will probably won't be implemented. I think the best solution for now is just don't /tpa to people while having items on you. (this solution sucks) It basically won't change it since /god and keep inventory is a think for a lot of people, and even if it changes it, the change is for the better since it is a step against p2w gameplay.