Interesting. The web client states in the "video" line that it detects that it is HDR. But when I look in the Android TV client there is no HDR tag. So I'm assuming that is what you are also not seeing in Kodi.
Jellyfin 10.10.7 (Docker)
Ubuntu 24.04.2 LTS w/HWE
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
4x WD Red Pro 6TB CMR in RAIDZ1