Stretched QGIS Hexbin in Google maps

I am very new to GIS so please forgive me if the question is naive, but I haven't found a solution yet.

I generated a mock hexbin in QGIS using MMQGIS plugin, with project set to EPSG:4326 and saved to PostGIS.

When queried as Geojson via Postgis, the returned data looks stretched in Google Maps.

I have tried to save in EPSG:3857 Google Mercator but that doesn't work either.

Creating the map in 3857 was the answer, however I did try before without success, however trying via DB Manager did the trick, the Target SRID was the missing piece in the puzzle!

When projecting data from a long/lat system to a Mercator projection, your data will always be stretched by a factor of sec(y) (i.e. $\frac{2 \cdot cos(y)}{cos(2 y)+1}$) in the vertical direction (derivative of Mercator equations that you can find e.g. here).