Thank you all, got it working when the dev “Cas” told me that libraster-libtorrent 1.2 is required instead of 2.0. https://dev.deluge-torrent.org/ticket/3444#comment:3
now it works.
Build your own:
or directly install: https://github.com/fastrizwaan/deluge_flatpak/raw/main/deluge.flatpak