Well, it’s about Peter Thiel, who also founded the Palantir surveillance technology company. As a source for his involvement with Brave, Wikipedia cites this TechCrunch article, which mentions funding from Thiel’s “Founders Fund”.
I’d rather criticize Brave for other reasons though, like being led by Brendan Eich or supporting crypto.
There is no downside to nested encryption, except of course the performance overhead. But this only really makes sense if each layer has an independent key and each layer uses an algorithm from a different family. Improper key reuse weakens the scheme.
For symmetric cryptography like AES the benefit is dubious. It is far more likely that the content is decrypted because the key was acquired independently than that AES would be broken.
However, there absolutely is a benefit for asymmetric crypto and key agreement schemes. This is how current Post-Quantum Cryptography schemes work, because:
Nesting one algorithm from each family gives us the best of both worlds, at a performance overhead: conventional asymmetric cryptography give us temporary security in the near future, and the second PQC layer gives us a chance at long-term security.