Android 14 Developer Preview 1 has just dropped, and according to PhoneArena, one of the features added is Advanced Memory Protection, with the Pixel 8 and 8 Pro being the first devices to get it in the public release version. This is supposed to combat "errors in handling memory in native programming languages," according to Google.
Another feature is Memory Tagging Extension, or MTE. Long story short, it increases the security of your RAM if you have a ARM V9 CPU, specifically preventing memory violations that can "break down the security of your device." The reason this doesn't work on Pixel 7 and Pixel 7 Pro is because Tensor G2 uses ARM V8.2.
A significant (but most likely not noticeable to the everyday person) change with Android 14 is that a significant chunk of it's code is written in the Rust programming language, rather then C or C++.
According to XDA Developers, Android 14 is also rumored to have a feature that should show what apps were installed in the background, which would crack down on bloatware from your carrier as well as other places. The feature will be called "Background Install Control." It could also be used to spot any Trojans that malware may have downloaded from the Internet.