If there is a seismic hazard in your area, then along with waterproof and fireproof, you should think about protecting seed phrases from earthquakes. In my opinion, the most dangerous elements here are building structures, such as various heavy objects, such as concrete walls and metal elements. When crushed and dropped by their own weight, these parts can damage the metal crypto storage and make the information unreadable.

How can this be prevented? I think it will be necessary to use thicker metal plates, or even better, several at once, like a sandwich. That is, the main plate with text on both sides is covered by 2 other plates that take all the damage to protect the main plate from deformations and damaged text. The multi-plate construction will have greater rigidity and will not bend like a thin piece of metal.

https://jlopp.github.io/metal-bitcoin-storage-reviews/reviews/cryo/ - something like this, but I would replace the threaded bolts with hard-fixing rivets (as a bonus, it will be immediately noticeable if someone opened your vault) so that the threads would not be torn off and the plates would not separate from the impact.

It is better to have an extra margin of safety than later to have difficulties with the readability of the seed-phrase during restoration.

Let's say you manage to make the storage strong and reliable, but another question arises. Will it be possible to find your seed-phrase under a bunch of rubble and will you be the one who found it?