I noticed a day or two ago that I posted something and had to go back and separate words. I wasn’t 100 percent sure it wasn’t my own error. But then just now a quote from another person’s post got a couple words “smushed together” (I checked, and it definitely wasn’t like that in their post that I quoted from), and I had to go back and edit the quote box to fix it. (It occurred to me that I might incur some technical penalty whether I did that or left it alone! LOL)
Which editor mode are you using?
I personally only use normal mode and I have never seen this issue. If you aren’t using normal mode I believe there are some issues, though off the top of my head I don’t remember what they are. My memory is admittedly a bit vague here, and I don’t have time to play around with it at the moment, sorry.
If you are fixing a quote because the editor mangled it, that’s no biggie. For other things like typos (which you aren’t referring to but just for the sake of completeness), we would prefer that you not fix those. If the words are smushed together in the original quote, leave them smushed. If they aren’t squished in the original quote, then you can fix that.
This thread may also be relevant:
https://boards.straightdope.com/sdmb/showthread.php?t=871872
I noticed that in one of my posts today. When I cut and pasted from a Wiki article, every word that had a hyperlink got concatenated with the words before and after it.