Blurry images in posts

After resizing and compressing all of my images, I went to review my site and found that some images were very blurry. Long story short, it turns out that the image size had changed from the size I had set, to a 300pxx200px version. Since the images are displayed on the post as about 820 px wide, they get upscaled, causing the blurriness. The only solution Ive found so far is to delete the image and re insert it into the post. You can see what I mean in one of the images in this post (the blurry png towards the bottom): https://www.circuitbasics.com/tda2050-diy-amplifier-build-guide/