In WordPress, as in most CMS, there is a functionality for creating thumbnails of uploaded images if they are large. This approach allows you to significantly speed up the loading of site pages by reducing the amount of data transmitted to the user, but at the same time creates many copies of each image with different sizes (depending on the image size and settings CMS there can be from 2 to 5 thumbnails for each of them). Thumbnail generation can be disabled in the CMS, but they can also be created by plugins or themes - in which case they will need to be disabled separately.
Disabling the generation of thumbnails can have a negative impact on the website loading speed, so it is not recommended to disable this functionality unless absolutely necessary.
To disable thumbnail generation, do the following: