After transferring my level 60 druid (Trisolaris) from Doomhowl to Dreamscythe, every quest I have ever completed have “reset” and I am able to pick them up again. This includes both faction-specific AND all neutral quests being reset.
For example, quests that I have for sure completed in leveling zones have completely reset, and I am able to pick them up again. Abandoning quests that are currently in my log does not let me pick up that same quest from the quest giver; and instead, NPCs offers me quests from the very start of the respective quest chain.
Further, my entire map shows all zones as undiscovered as well - although all my flight paths have been retained.
I submitted a ticket about this and there unfortunately is no way for them to restore my “lost” completed quests, had I known this was a possibility, I would have rather left my characters on Doomhowl after death. I have used free realm transfers before in the past (not on anniversary realms), and have not run into this issue before.