This world zone lag has been happening off and on since BFA launched. I feel especially bad for players on Oceanic servers where it’s been the worst, but I experienced it on Turalyon and now Arygos throughout the entirety of BFA.
Now SL has has carried the issue over, well past one year after said issue was acknowledged in the known issues thread linked below. When are we going to get a fix? The state of gameplay in the world when the issue manifests is completely unacceptable for the year 2015, let alone 2020.
https://us.forums.blizzard.com/en/wow/t/known-technical-support-issues-updated-july-21-2020/22909/5