Some pets still gather less than 5 pet materials even in a full node

This is one example but the situation still repeats, at least for me.

With a full node of 20 pets materials and 4 pets around, no other player in the node, the result was 2 pets gathered 5 materials each (as expected), but the other 2 gathered only 1 each , remaining 12 materials uncollected

Tried to find a reason like the 2 pets with only 1 material collected were the last ones that gathered from the all 4 or because they were leveled up at lvl 1 (this is why they also received XP) and for some reason they remained at 1 mat/pet as before or the type of the pet maybe.

But I had before a Slime at lvl 0 who collected first from the another full node also only 1 material, so I can't figure out the reason why some pets gathered below 5 materials even from a full node and no other players in there