What are the additional threats of "plain" AES in contrast to DTLS?
Before I start explaining the additional threats, I will first describe what DTLS does and what it does you protect against.
The PSK "Handshake" of DTLS consists of sending nonces (both sides; server random, client random) and the identity (so the server knows to which ...
[D]TLS provides quite a bit of protection beyond just confidentiality (encryption). It verifies the server identity (authentication), protects against message corruption or tampering (integrity), prevents replay attacks, and can provide forward secrecy (no ability for an attacker to decrypt a recorded message even if all persistent keys later become known to ...
Key Derivation functions like PBKDF, KDF1, and, HKDF can use a single password to derive a key. To derive an additional key with the same password the common approach is using info as in HKDF which has two steps.
Extract : HKDF-Extract(salt,IKM)->PRK
IKM is the Input Key Material
OKM is the Output Keying Material
See the links below for details about several bugs that were reported in 2019 concerning weak random number generation, and a flaw in the way that the IV is generated, in versions of 7zip at that time:
It seems that these bugs have been fixed in later ...