Steps to reproduce

1. Go to the end.
2. Drop items (e.g., dye fighting the dragon so your equipment drops).
3. Go back to the overworld (e.g., respawn)
4. Wait 5 minutes. (e.g., travel back to the end portal you used in step (1))
5. Go back to the end, to the spot where you dropped the item.

Expected results

You can collect your items.

Observed results

The items have despawned.

I was fighting the ender dragon and died in the process. I did gear upYou in my home base, which took longer than five minutes and when I returned into the end, all my items were gone.

So I did some testing. I used carrots and did drop them at certain places in the overworld, the nether and also in the end. 

I did drop some carrots at the following places: next to my re-spawn bed in my house (which is close to the world spawn point), at world spawn directly in the over world, in a far out dessert more than 2000 blocks away from spawn. I also did drop some carrots in the nether (at the corresponding coordinates where the spawn pace in the over world is) and around 1000 blocks out in the nether. then I jumped into the end and left some carrots at the main island next to the end gateway, flew around 1700 blocks and left some carrots there at an end city. then I flew away to the next end city which was around 2200 blocks out. did throw some carrots on to the ground and watched them de-spawning. then I flew back to the end city. carrots still there. then I flew back to the main island. carrots GONE. Jumped back through the end gateway. carrots next to my bed and at the spawn point still there. so I jumped through the nether portal and also in the end at both locations the carrots still there.

So only at the main island in the end dimension the things are de-spawning after five minutes, no mater if you are close to it (load the chunks) or not. in all other spots I have tested the despawning counter is only active when you are close to it and do load the chunk(s).

The ender dragon fight and loosing my stuff happened in version 1.19.83. the test with the carrots I did in version 1.20.0 so it is confirmed in two versions. and I'm sure when I did that in older versions of 1.19 it also happened when I did fight the ender dragon.

So why stops on all other places when no player is present and does load the chunks but not on the main island in the end?

I'm playing on Windows 11 and the world is on a REALM, but during that time is was the only person online as we are only two playing on this REALM.