Seems to be related to wordpress and working with translations. Haven't been able to pin if it is wordpress core related, or specific plugins. When you find those results on google, all the sites I saw it on were using wordpress.

It seems like a missing placeholder?

There's one report of this for the Polylang plugin [0]

And another reference in another plugin's help docs [1]

[0] https://wordpress.org/support/topic/i-have-some-error-with-t...

[1] https://docs.gtranslate.io/en/articles/1348921-how-to-edit-t...