Problems with rebuilding of existing images

[numis]

Hi all! Faced the following problem:

System-Posting-Images and Videos-Maximum image dimensions to display(reduced by me). 

Аfter rebuilding the thumbnails of the existing images, their quality get worse, not the size. Size remains the same, the text in the image in this article was readable, for example:

Thumbnails for new images works good as it should be:

 

Edited March 24, 2021 by numis

[kotaco]

+1