Bad quality of thumbnail image

Hello,

when an image that has a higher resolution (e.g. 1500px) is selected as a featured image, the post_thumbnail in grid has a bad quality. This is because the orginal image is taken to generate the thumbnail:

in ajax-filter-posts.php, line 312 is the code:

<div class="am_thumb">
	<?php the_post_thumbnail('full'); ?>
</div>

when we change it to:

<div class="am_thumb">
	<?php the_post_thumbnail('medium_large'); ?>
</div>

the image generates in good quality.

Could you add an option to the shortcode that would be responsible for changing the size of the photo for generating the thumbnail?

Best regards.