Players on the death screen still cause spawners to spawn.

The bug

Dead players within the range of mob spawners and spawner minecarts still cause them to spin and spawn mobs, just as if they were alive. It isn't until this player presses respawn that the spawner ceases.

How to reproduce

1. Place a mob spawner

   /setblock ~ ~ ~ mob_spawner default replace {SpawnData:{id:"armor_stand"},SpawnCount:1s,MinSpawnDelay:40s,MaxSpawnDelay:40s,RequiredPlayerRange:64s,MaxNearbyEntities:32767s}

2. Kill yourself but don't press respawn

   /kill