When I run a new page, I must specify size of the viewport using the setViewport function:
setViewport
await page.setViewport({ width: 1920, height: 108
I may be very late on this. Nevertheless for others, try:
const browser = await puppeteer.launch({defaultViewport: null});
Set the defaultViewport option to null as above to disable the 800x600 resolution. It takes the max resolution then.
defaultViewport
null