Guild Wars 2

All my beta characters are gone. Is it a bug or intended?

Probably intended
“Due to large back-end changes to core systems that have corrupted some of the beta data, your characters from previous beta weekends will not be available for BWE3—everyone will be starting with fresh beta characters.”
https://www.guildwars2.com/en/news/the-final-beta-weekend-event-begins-october-2/

It is intended. When they announced BW3 (beta weekend 3) they also announced they had some data corrupted with the beta toons and said they were going to be removed.