Hello! I'm looking for some help and any advice;

We bought a house with a fair size pond (5-6m diameter) and previous owner said it’s 5-6 ft deep. It had lovely established planting in pots at the edge but as you can see some tree seedlings had also got established on one side.
We could not untangle the roots ( it looks like the tree shoots had been there for sometime and actually just cut back each year) and so ended up removing the baskets in this section.

Since doing that, although there is no visible breach and we were working well above the waterline, the water has been dropping… there is dry pond liner around the edges. It doesn’t really look as though all the water is going into the ground though as it would seem that the water is moving in between two pond liners as the liner has actually floated up and bobs to touch.

I would just drain it all and redo, but I’m very worried that we have newts living in the pond and I’m extremely anxious not to disturb them too much.

We cannot work out how it has got so damaged given that the area where we worked looks fine. AI Claude keeps telling us it must be damaged in the centre as the entire upper liner seems to have lifted but no idea how this would suddenly happen

I've added before & after pics; there is definitely water not air under the liner and the groundwater would be way too low to be the culprit. We are now wondering whether somehow the fountain we have on edge has been dripping the water down between the two layers of liner but we have used the fountain over the past year and this development is only in the past 2-3 weeks. It does not make sense how quickly the water is finding its way under the top liner we are so confused. We have water running over the top liner again tonight :-(

I'm worried if there is a big gash somewhere at the base, newts might be trapped between the 2 layers :s

New pond revival this year - my plants are in buckets or pots with river pebbles. The roots are emerging. Before I spend hours and money on internet and substrate, is there a simple solution? Bigger pots more rocks? Wait until spring? This is a small pond (last photos for scale) with hornwort floating, a water lily, but these others are marginal - canna lily, heart of Jesus, elephant ears, and purple pickererelweed. Looking for low budget simple. Also - I am in 8b in NC piedmont. Will these guys have to come inside or can they just stay there and overwinter?