You didn't say "programmers should be aware that rust doesn’t automatically mean safe". You said:

People just think that applying arbitrary rules somehow makes software magically more secure...

You then went on to mention unsafe, conflating "security" and "safety"; Rust's guarantees are around safety, not security, so it sounds like you really mean "more safe" here. But Rust does make software more safe than C++: it prohibits memory safety issues that are permitted by C++.

You then acknowledged:

I understand that rust forces things to be more secure

...which seems to be the opposite of your original statement that Rust doesn't make software "more secure". But in the same comment:

It’s not not like there’s some guarantee that rust is automatically safe...

...well, no, there IS a guarantee that Rust is "automatically" (memory) safe, and to violate that safety, your program must either explicitly opt out of that "automatic" guarantee (using unsafe) or exploit (intentionally or not) a compiler bug.

...and C++ is automatically unsafe.

This is also true! "Safety" is a property of proofs: it means that a specific undesirable thing cannot happen. The C++ compiler doesn't provide safety properties[1]. The opposite of "safety" is "liveness", meaning that some desirable thing does happen, and C++ does arguably provide certain liveness properties, in particular RAII, which guarantees that destructors will be called when leaving a call-stack frame.

[1] This is probably over-broad, but I can't think of any safety properties C++ the language does provide. You can enforce your own safety properties in library code, and the standard library provides some; for instance, mutexes have safety guarantees.