There are many possibilities. I understand that are more marine animals that burrow than land animals. So burrowings themselves don't establish anything, but rather the kind of animal that created the burrowing.
There may be layers that predate the flood and layers that occurred afterwards. In addition the flood was a year long event. There may be periods during which land was exposed prior to being reflooded by the release of waters trapped at higher elevations.
However if it was laid down over eons, as evolutionists claim, the burrowings that would have occurred, would have made the strata almost unrecognizable. Water erosion would have carved it into hills and valleys, some of which would have refilled. It's the extreme rarity of the findings you cite and the lack of erosion that is evidence that they were laid down rather quickly and.
Except that the owners of the burrows are often found fossilized within those burrows and terrestrial animals have distinctive burrows because of the nature of tunneling in air vs. tunneling underwater.
There may be layers that predate the flood and layers that occurred afterwards.
The former means the world is a lot older than allowed by YECs and the latter indicates that a lot more time has passed since the flood than YECs can account for. Not to mention there is no geological evidence for a single global flood anywhere.