Greetings Cecil!
When I wrote that post a few minutes ago, I didn't choose the best words.
I have seen liners, improperly installed, come off the bottom.
If there's any air under the liner, or if water can percolate under the liner in spots where there's air pockets, I have seen a liner rise. When it rises, it pulls away from the shore, and the pond must be drained and the liner re-installed.
If the liner isn't installed above the water line, and there's porous soils, that too can compromise the effectiveness of the liner.

Teach a man to grow fish...
He can teach to catch fish...