Tested in GC 12.0.4 (6160):
Scenarios from 2b now both worked
2) Save for web:
b) As WEBP + Embed Exif ON + Reduce to 72 PPI OFF + (Lossless || Quality 80) + (Sharpen None || Sharpen 20%)
→ All results in WEBP with the original PPI preserved which was 144 PPI.
Changing title to [Fixed].