Confirming behaviour on 1.16 Release Candidate 1. In 1.15.X and previous versions, spectators on a team inherited the colour of the team and lose the italicized form in the tab player list.
Confirming for 1.14 Multiplayer server
Minecraft Crash Report ----
// Sorry 😞
Time: 4/24/19 9:55 AM
Description: Exception ticking world
java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909)
at java.util.ArrayList$Itr.next(ArrayList.java:859)
at bhu.a(SourceFile:72)
at vg.a(SourceFile:317)
at net.minecraft.server.MinecraftServer.b(SourceFile:827)
at ug.b(SourceFile:343)
at net.minecraft.server.MinecraftServer.a(SourceFile:764)
at net.minecraft.server.MinecraftServer.run(SourceFile:632)
at java.lang.Thread.run(Thread.java:748)
A detailed walkthrough of the error, its code path and all known details is as follows:
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I operate a busy pure vanilla server using the Mojang server jar and I confirm this issue is impeding my staff's ability to go into spectator with some degree of being incognito to catch hackers and griefers. Granted that the spectator color is slightly translucent but we were able to have staff in spectator mode be less obvious while investigating player issues. This has been so since at least Minecraft 1.8.X from 2015 and its suddenly being removed.