Featured image is blurry in blog site

Hello, can anyone assist me on what to,?
The featured image in my blog is blurry, but after clicking it the normal quality shows up!
I’ve tried alot settings and it didn’t work. Someone asked this in 2019 and was able to get it resolved, i don’t know how to resolve mine!
Please help.

Set your featured image on default size 1200 x 628 pixels.
If you put in WordPress website, so their is a plugin available who solved your blurry image issue.