Tor has extra guard connections

We lowered the number of directory guards to 2 in part because I suspected it was causing extra guard connections to get made and kept open, leading to fingerprinting: tpo/network-health/team#325 (closed)

However, a forum user pointed out that their Tor is using 3 guards still: https://forum.torproject.org/t/tor-browser-connecting-to-3-guard-relays-simultaneously/9819

I also just checked my Tor, and it is using 4 guards...

So there definitely is some problem with Tor opening too many guard connections, and then just keeping them open for as long as it wants.