Problem with using add_image_size in thumbnails – wrong proportions at upload

Hi, everyone!

Having a featured image width problem at https://balfour.webson.ee/en

The WP theme (Solid) is using add_image_size( 'service-thumb', 300, 100, true); in functions-setup.php to automatically set the thumbnail (featured image) size for the two service boxes on the homepage (Property development, real-estate consulting).

Now the problem is, that originally, the code specified a width of 180 for the featured images, which I changed to 300. It does display the image at 300px width now, BUT, it looks wrong when I upload a 300×100 image. Somewhere along the way when uploading, it automatically changes (crops?) my picture to 180×100, which it later streches to 300×100.

So even when I upload a 300×100 image, the theme resizes it to 180×100, and then streches it to 300×100 again. Can anyone please give some hints as to what should I change? I havent found any additional 180px in the code that I could change to 300.

Thanks a lot,
Jaan-Matti