As you know, netherite items and ancient debris are supposed to float in lava. I have discovered, however, that this is not the case all of the time. Once, I died in a bastion remnant lava pool that was relatively close to my portal. I was able to get back to it with relative ease. What I noticed, though, was that there were no items floating in the lava at all. Turning chunk borders on, I noticed that the area where I died was in basically the same chunk (which was unloaded when I came through the portal). This means that either none or all of my items would have despawned. For me, however, there were only some of them. I decided to go into a creative test world to test what happened. I created a small lava pool, threw a netherite ingot  into it, unloaded the chunk, and flew back within 5 minutes. The ingot was gone. I haven't heard of other reports similar to this, so I am not sure what happened or if it's on my side.