Unless you’re a security researcher, political dissident, enemy of a dictatorship, you have the secret of unlimited energy, or you actually have proof in hand of any of the crazy conspiracy theories going on out there, your worry level should hover about at none.
It’s currently not something that’s just going to happen. You’d need a whole bunch of converging events in order to get to write the firmware… that involves somehow installing software, root level access so you can write to the system, exploits galore just to get to this exploit.
At the point you’ve got root you could simply install screen capture and phone recording software. No need to risk bricking the phone to modify a chip’s firmware.
You’re more at risk currently of your conversation being intercepted by someone tying a string to your phone, keeping it taut, and attaching a red solo cup to the other end and listening in from another room without you knowing.
Good that they caught it, good that it’s being patched, plenty of other ways that are easier to intercept your conversations and text messages that this doesn’t cover and the fix doesn’t fix.
Patch up when you get it.