I have the same problem with a clean install of Kubuntu 24.04. TBird version 2:1snap1-0ubuntu3. My Downloads folder is a symlink to a folder in a different partition on the same disk, both partitions are formatted as btrfs. Installed the Flatpak version 115.10.1 which is working.
I have the same problem with a clean install of Kubuntu 24.04. TBird version 2:1snap1-0ubuntu3. My Downloads folder is a symlink to a folder in a different partition on the same disk, both partitions are formatted as btrfs. Installed the Flatpak version 115.10.1 which is working.