What is this buff in The Virtuous Cycle?

That looks a lot like the image for the consumable Simple Lute on the game wiki, which has a description of:

Sit on the floor and lure nearby enemies. The sheer audacity incites enemies to violence from a great distance

This site states:

  • Allows you to play music, although you'll play poorly until you become more familiar and the lute can break after a few uses.
  • Familiar: Draws enemy aggression from a fairly long distance (thanks to your "sheer audacity"). Useful for kiting enemies to fight you on more advantageous ground.

Turns out this buff is granted by Simple Lute in my inventory. They are different from the main game and provide various bonuses in the DLC. Can be purchased in the Fallgrim Tower, they are located on the wall not far from weapons stand.

You can carry only 1 lute at the same time, effects are the following:

  • Simple Lute, costs 25000 Tar: +30 Max HP passive bonus and health regeneration on use. Can be used up to 3 times.

  • Impervious Lute, costs 50000 Tar: +30 Max Stamina passive bonus and stun resistance buff for 2 minutes on use. Can be used up to 3 times.

  • Clockwork Lute, costs 75000 Tar: +10 HP, + 10 Stamina, +1 Max Resolve passive bonus; grants Endless Unborn perk on use. Can be used only once.

Lutes are not lost when you replace them with another one - you can get them from the safe wall second time for free. Not sure if you need to repurchase them after they break, for me passive bonuses look more useful than active ones.

Same info on actual screenshots:

Simple Lute Impervious Lute Clockwork Lute