Since 2019, Danmark's National Bank has been upgrading the current banknote series and preparing for a new one (set for release in 2028-2029).
The upgraded 50 Kroner note should be out from today, the 2009A issue.
I'm looking forward to add it to the catalog, when someone create it/find it :D
About the security features:
https://www.nationalbanken.dk/en/what-we-do/notes-and-coins/security-in-banknotes-and-coins
The PDF about the 50 does not yet exist in English:
https://www.nationalbanken.dk/media/4qqkixgw/infofolder-sikkerhedsopgradering-50kr-dk-2026.pdf