What does a pair of interlocked arrowed squares mean?

I had my music app open today (Samsung Music) and I noticed an icon I'd never seen before.

It disappeared before I was able to press it so I was not able to take a screen shot of it either. It looked something like this:

interlocking arrowed squares

I haven't seen it since, and so far I have been unable to search for a matching icon online, e.g. by doing a reverse image search which often finds close matches.

It was in a row of icons at the top right of the screen:

?? ? ılı.ı ⁝

  • ?? mystery squares icon
  • ? volume icon
  • ılı.ı "graphic equaliser" icon
  • ⁝ three vertical dots menu icon

There are separate icons at the bottom of the app for random order and track repeat, so it doesn't seem to be either of those.

What does this icon mean?

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