Is my iPhone cloned

The echoing seems more like a generic problem with an iPhone microphone or related hardware, and its noise cancellation processing.

If not already running it, update to current iOS (iOS 16.4 for an iPhone 12), and force a restart. if the problem persists, contact Apple Support and see what they suggest.

As for text messages from unknown senders, those can too often be scams and scams and spam, advertisements, spam, and other rubbish. And spam. And scams. Sending numbers are routinely spoofed, too. I usually mute unknown senders. Almost certainly completely unrelated to the microphone issue.

The collective wisdom of Google search results ranking tends to be fairly low on a number of topics. There’s been malware being offered via Google search results lately too—fake search results—though that is unlikely to effect an iPhone user. Some websites have been making utterly bogus “you have (3) viruses!!!” claims and advertising junk iPhone apps, though. Lots of rubbish on the ‘net.

Casmore2012 wrote:

Is my iPhone cloned

If you suspect your SIM has been cloned, contact your carrier.

As for the rest, start here to review your security: Personal Safety User Guide - Apple Support

No. What prompts you to ask?

If you did not jailbreak your phone, you do not have 'spyware'.

this used to be correct…Apple is not hacker proof anymore. Speaking from personal experience with non-jailbroke phone…sorry