Repro steps:

• Give yourself a player head with a custom owner. For most consistent results, use a new player name every time:

  /give @p minecraft:player_head{SkullOwner:"PearlescentMoon"}
  

• Place an armor stand
• Place the head on the armor stand

Results:

• Sometimes the players flicker between the default player head and the custom one

Expected results:

• Only the custom skin shows