It's probably a lot of things coming together - until now attendance was propped up by revenge travel and people wanting to get their Disney fix, plus people that typically go every 2-3 years were waiting during covid years so all that got lumped together and now this is just an "off year" for many
Combined with many people discovering other things to do with the money they had during covid and just exploring other vacation destinations, add in the increased complexity and costs with a Disney trip and many people just say "forget it, other better/easier things for me to do with my time and money"
Now Disney needs to try to attract people back - seems focus is undoing something of elements recently installed and trying to make things more like what they were pre-pandemic (which still charging more, but at least removing some barriers)