u/PurposeNo7234

I have noticed that since the 1.26, some farms that automatically kill mobs dont use the trident killer anymore and instead use this system of a mob with spear in a minecart like the one in the picture (Which is a screenshot of a video tutorial for a creeper farm).

What is the reason behind this change? What are its advantages?

I have this Realm with the Realistic Landscapes world from the Marketplace. The problem with it is that it is stuck in the 1.21.90 because of it and i would really like to update to the new versions.

Is it possible to update the world even if it involves corrupting certain part of the world or something like that? or is it genuinely impossible, I am looking for any idea/fix.