You stood up with purpose. You walked down the hall. You arrived in the kitchen. You have absolutely no idea why you're here.
This isn't aging. This isn't distraction. This is what scientists actually call the doorway effect; and it hits us harder.
The doorway is a context boundary. When you cross it, your consciousness does a soft rebuild. New room, new context, new environmental cues.
For neurotypical brains, the intention ("I need scissors") usually survives the rebuild because their working memory buffer holds it through the transition.
For your brain, the intention was one of many items in an already-full buffer. The context switch dumped it. The physical environment changed. Your consciousness rebuilt around the new room's cues. The scissors were collateral damage.
This is why you stand in the kitchen opening cabinets at random. You're hoping an environmental cue will reload the intention. Sometimes it works. Sometimes you just eat cheese and go back to the couch.
You didn't forget. Your intention didn't survive the reconstruction.
Hot tip: Walk back to the original room. The old context usually reloads it.