ECG available in the region, but failed to setup

Due to regulations in your country or region, ECG version 1 or ECG version 2 might not be available. Here's how you can verify which version of the ECG app you have on your Apple Watch or iPhone:

About ECG app version availability on Apple Watch - Apple Support

If the versions are different, that could be the problem.

So your Watch is from Malaysia but your iPhone is not? That would be a problem.

Same thing goes to me. I don’t understand why this kind of thing still happening even after updated the latest software 7.5

Both have to be available for ECG within the same region. Click on the Get Support link at the top right of this page to see if this will be a problem. Your watch and phone are up-to-date for OS versions?