In Tasha’s Cauldron of Everything, the Swarmkeeper Ranger’s "Gathered Swarm" feature states the following (emphasis added):
A swarm of intangible nature spirits has bonded itself to you and can assist you in battle. Until you die, the swarm remains in your space […].
In a recent encounter, my Swarmkeeper just died but was resurrected by the party’s Cleric. Because they’ve died, does this mean that the swarm is lost to them forever?