It depends on what kind of patent. I just googled the term I had used before, and it is indeed what I expected it to be: https://en.wikipedia.org/wiki/Design_patent
And yes, that name is stupid. That's why I am happy that my native language, German, has a better distinction between "Patent" (what you described) and "Geschmacksmuster" (design patent).
About patents being public: They are. That's because the idea behind patents is that after they expire, anyone can use them to build the technology they describe. The temporary exclusive usage rights that they offer are meant as an incentive for inventors to publish their findings. The only problem is that the legal situation did not keep up with the creativity of patent lawyers... (I will stop now, otherwise this will turn into an endless rant about how broken the patent system is.)
I am not in the position to decide which tech we use at the studio, however, as a Senior my voice is certainly heard when it comes to tech decisions.
And for Unity I can only say: No tech is worth the risk of dealing with such a shady company.