Can upload sketches but serial print from the code is garbage

Note: I'm posting this here because I don't think this is a coding issue, but rather a problem with my install of the Arduino IDE or the standard libraries.

I'm having an odd issue with serial output from new sketches. Also this behavior is happening both in the Arduino IDE and PlatformIO. I've tried this with both an Arduino Pro Mini and also Nodemcu ESP8266. The behavior is the same with both.

I can compile and upload the sketch and I know it is running on the Arduino as I can see the LED flashing. However the Serial.print output is garbage. It is like it is just a little bit off the timing for the serial data rate as occasionally I can see one or two of the correct letters at the start of the string.

Below is the simple test sketch that I'm using. The serial monitor is set to match the 74880 baud in the code. Though I've tried all of the speeds and all are worse than the defined one.

void setup() {
  // put your setup code here, to run once:

void loop() {
  // put your main code here, to run repeatedly:

This is the output from the ESP8266 after a reset. You can see that the interface is working ok as the boot info displays correctly but then the Serial print is garbage.

19:18:49.525 ->  ets Jan  8 2013,rst cause:2, boot mode:(3,7)
19:18:49.558 -> 
19:18:49.558 -> load 0x4010f000, len 3584, room 16 
19:18:49.558 -> tail 0
19:18:49.558 -> chksum 0xb0
19:18:49.558 -> csum 0xb0
19:18:49.558 -> v2843a5ac
19:18:49.558 -> ~ld
19:18:51.132 -> ⸮x]]]]MM⸮M]]M]⸮}M                          <----- from the sketch.

I'm running Arduino IDE 1.8.13 on this Mac and anything I compile and upload seems to have this problem. On my laptop (also macOS) I'm running Arduino IDE 1.8.12.

This really seems to be an issue with the code that is getting written to the Arduino because I can compile and upload the sketch on the laptop and if I plug the Arduino into my desktop I can see the Serial print output just fine. However if I compile and upload on the desktop then the Serial print is garbage on the desktop and also in the serial monitor on the laptop.

I've spent the whole day googling and trying things but I just can't figure this one out. I'm getting close to trying to wipe the Arduino IDE and reinstall from scratch, but that just doesn't seem like a fun time.

Again I'm pretty sure it isn't a baud rate config issue as I've checked this repeatedly and everything works fine on the laptop. Also it is the same behavior on both the ESP8266 and the Pro Mini. It really is acting like something is amiss (perhaps corrupted?) in the standard Serial library or some other dependent code. I've been writing and uploading code on a nearly daily bases and everything has been fine until just 2 days ago when this started.

Any help is appreciated. I've been have a blast building things with Arduinos and this is definitely putting a damper on things.
Cheers, K

Oh my goodness! Reading thru my own posting I noticed my silly error. I've managed to place the Serial.begin() inside the "loop" rather than "setup".

It often helps, sometimes even before you submit the post you can see the error.