So there are these weird shadows I found while I was playing in survival.  It seems to act like it is night even though it is in the middle of the day.  I saw a creeper spawn in one of them.  You cant get rid of it (as you can see in the video that is attached) unless you place torches at the very edge of it where it switches back to daylight.  I don't know what's going on, or if this was an existing issue in the previous snapshots or version.  I couldn't find anyone else talking about this (probably because they are paying more attention to the caves).  Hopefully you can fix this bug.  (the video was too large so i put the video on my youtube if you want to see it in more detail, here's the link https://youtu.be/Lh_L1RDNx8Y)

edit: a lot of people seem to have this problem the more i look into it, so hopefully mojang fixes this by the time the next snapshot/full release of 1.17.0 comes out