Allay holding item breaks lead and goes to player when there are a lot of drops on the ground

I have an allay holding a totem of undying attached to a fence post by a lead.  About 50 blocks away several plots of farmland growing wheat.  When I go to harvest the wheat, leading to a large number of drops on the ground, the allay breaks free and comes over to me.  It has done this twice, and it doesn't do this any other time.  (This is on a server.)