Null issue when pasting image(s)

[skywalker22]

For the last couple of weeks I am noticing an issue when pasting, or copying an image (or more of them). There is appearing some small blue square, which results in a word "null" after saving the post.

It looks like:

null

PS: null is not what I wrote.

The upper image is just an example of copying an image and how word null appears. Before saving the post, there is that blue small square, after saving, that square disappears and its replaced by null word.

[okopanja]

Already reported: you are not alone

This is annoying as hell