unknown https addresses appearing in Recent Documents

[JiminyCricketRules]

I’ve never seen this before but in my Recent Documents today I find three unknown https addresses appearing as some of my recent documents. I would never knowingly load a web page into Libre Office and if I wanted to download a document for opening into Libre Office I would download it and save it first before opening it. I do not knowingly use Libre Office within a browser.
Can anyone explain how this could occur? Is this some kind of attempted hack or vulnerability? Many thanks for any thoughts on this…

The three documents are as follows:
https:postmessageRelay
https:anchor
https:bridge0.000.0_en.html //note - I have replaced numeric digits with zeroes in this address

[JiminyCricketRules]

I am wondering but not sure if either of these two activities could be related or not…

1. It might be possible that around that time in the order of (Recent Document) events I could have copied text (possibly including html) from a web page news article or other web page and pasted it into an odt file to save as a record of the given web page. I’m wondering if this action (copying and pasting) could inadvertently cause this weirdness. I am not aware of having clicked any links and this is definitely something i would try to avoid but I guess this sort of thing could always be done by accident.
   However, I would comment that I have copied and pasted web pages and saved them as odt files very many times before and I don’t think this has ever happened before.
2. A second (unusual for me) activity that I undertook at around that time was to download data from a particular cloud type data service having been provided a third party cloud link by a supposedly trusted source. I opened the link provided in a browser and I hit a download button to save a zip file to my hard disk. The zip files contained csv data files which I opened in Libre Office. Some of them were very very large to the point where Libre Office Calc could not open all the rows but I don’t think this was a problem - it just opened the maximum number it could and i was able to scroll through the data doing some initial checks.