That is a turn-off transient and isn't harmful.
And this is completely wrong, sorry. First of all it depends on the circuitry of the amp.
Secondly, many high-end dollar amplifier designers believe that said relays are detrimental to the SQ of an amp.
And so they run without 'em. However proper procedure is also a known thing, where as with cheaper products such as Schiit, etc,
such 101 basics may not be known.