Yes. Install Greydwarf Eyes 0.2.0 on every client and the host or dedicated server. All use the same GreydwarfEyes.dll. A mod-manager profile has its own plugin and configuration directories, so verify the profile used to launch the game.
Configuration is not automatically synchronized or enforced. Copy matching gameplay settings in BepInEx/config/local.valheim.greydwarfeyes.cfg to all peers while the game/server is closed, then restart them. Wreath comfort and recipes are gameplay settings. Wreath / Brightness is a personal cosmetic setting and can differ between players. Keep only one DLL copy per installation.
Eye-mark is designed to follow the target when simulation ownership changes, retaining its remaining time and piercing bonus. Subsequent piercing hits from any attacker can benefit; repeated marks refresh the duration without stacking the bonus. Normal PvP, blocking, resistance and immunity rules still apply. Mods that replace projectile attack statuses may conflict.
Automated checks do not replace an in-game test. Live multiplayer, wreath placement/comfort and ownership changes remain unverified.
Removing the mod
Dismantle placed Watcher's Wreaths. Remove the custom torch, arrows, mead bottles and mead bases from inventories, equipment, storage, item stands and the world before uninstalling. Finish and empty fermenters containing this mead base. Valheim cannot resolve these custom items and build pieces without the plugin. Close the game and server before removing the DLL from every peer.