In a relay's logs:

Oct 20 10:31:47 XXXXX Tor[YYYY]: We're low on memory.  Killing circuits with over-long queues. (This behavior is controlled by MaxMemInQueues.)

Oct 20 10:32:11 XXXXX Tor[YYYY]: Removed 1565259696 bytes by killing 1 circuits; 40008 circuits remain alive. Also killed 0 non-linked directory connections.

Tor removed ~ 1565 MB by killing 1 circuit? Seems like that can't be right?

Earlier in the log I see "Based on detected system memory, MaxMemInQueues is set to 1500 MB." So either it's dumping the entire queue here, or the output is misleading. Or perhaps I don't understand how it works.

It doesn't seem to be impactful; I'm just curious what's going on.