Is this new shower tray defective and would you install it in this condition? The void where the wax deposits were (last photo) is between 4m-6mm deep.
Hard to say about the top surface as it is still in the packaging. Should the base be level and have the reinforced supports across the full length not just half? It will be mounted using a riser kit in an apartment.
Speak to your merchant and see what they say. They may be happy for you to unpack and inspect.
Personally that doesn't worry me much as I would just make sure its well supported with tile adhesive. I won't ever fit a tray that size on legs as it will just creek and bounce like crazy