Image filename problem – number string being added to the end

Tech question here I’m hoping someone can help me with please?

It appears that all my images in my blog posts are getting a string of numbers (prefixed with ‘e’) added to the end of a file name. This is impacting jpg and png files. I always use unique file names and images for SEO purposes and this wasn’t previously a problem. I thought it had only recently started happening but I’ve just checked back through my media library and it’s affecting virtually all my images. Previously none of my older images had this suffix in the filename so I’m assuming something must have happened recently to add it to ALL my images.

Now I’m noticing it happening as soon as I upload an image.

For example:

I name a file ‘puerto-morelos-snorkelling-tour-mexico.jpg’ but when it’s uploaded to wordpress it’s showing as ‘puerto-morelos-snorkelling-tour-mexico-e1522303668828.jpg’

Does anyone have any idea:

a) why this is happening?
b) how to stop it happening?
c) for all the images that have been affected is there a way I can change these in bulk without having to go through them all individually?

I have nearly 100 blog posts with images being affected so going back through them and changing them manually isn’t an option – even if it was it wouldn’t work at the moment as the name instantly changes on upload.

I need to get this sorted as it isn’t good for SEO so any help would be much appreciated – thank you!