For the UK specifically (see the comments above), EV-CPO lists about 100 "hidden" cars (currently unlisted) for sale. On the advanced tab, click the "Display only 'Hidden' cars? Yes" to see these vehicles.
Yes, Tesla is playing games with the listed/published inventory, they always do. There have been several times where they removed 90% of the listed cars, and then weeks later, added them back with even more, previously unlisted, cars. I suspect this same cycle will continue.