I'm running Oreo 8.1.0 on a Xiaomi A1. In the status bar, I see the following three similar icons beside the WiFi icon, never more than one of them at a time:
One of them is a solid equilateral triangle, with a vertex at the top, occupying the top half of the status bar.
One is a solid equilateral triangle, with a vertex at the bottom, occupying the bottom half of the status bar.
And the third is the combination of the other two.
I can't find any info about all of them by searching online, nor at Material Design's Icons.
What do they mean?