Full Width Image, Full Width Template – BLURRY

HI All,
Just spent 20 minutes googling / reading.

so I have a 2500px wide image my colleague wants to fill the screen.

In 2020 theme I choose an image block and make it full width. (shows full pixel count wide). I use full width template.

The image is always blurry.. My reading said maybe this is an issue with wordpress?
Is it user error?

Would love to understand my options and any workaround.