Post grid showing pixelated featured image

I have built a front page for my website (Lavelle theme) using Elementor, added the Essential Add-ons for the post grid… but the featured images from each post are appearing pixelated or blurry.

The size of the post grid thumbnails are 349×142
These are used here: https://www.thriftlove.ca/home/

The size of the uploaded featured images are 749×305
These are used here: https://www.thriftlove.ca/blog/

I’ve tried changing the media sizes, changing the media sizes to 0, installing plugins to optimize… thoughts or suggestions?

The page I need help with: [log in to see the link]