In the Oxygen icon set "download" has been an icon on its own, and thus being used by many applications for actions being about copying something from the network/internet to the local system. There has been also "edit-download", which is symlinked to "download".

In the Breeze icon set though "download" is itself a sym-link to "document-save". With the resulting icon, being the floppy disc and thus the typical symbol for "save to storage", misses the annotation of what the location of the storage is, it could also be the server. Which is a regression for all programs being developed based on oxygen icons, given download is something different to save. It breaks applications which have a mixture of icons based on the oxygen symbol metapher, where the arrow as indicator for download has been relied on.
See e.g. "download-later" and "download" icons in Breeze seeming to be about something really different, while actually the first should be just a delayed version of the second.

So IMHO "download" should be rather a sym-link to the "edit-download" icon (which in Breeze is an icon on its own).

There seems almost no maintained application anymore which uses the "download" icon in KDE repos (cmp.  https://lxr.kde.org/search?_filestring=&_string=%22download%22&_casesensitive=1 and ignore false hits), the maintained ones had been ported to use "edit-download" instead (I just did that in KDevelop).
Still would be nice for 3rd-party apps and anyone developing based on current Oxygen icon set to have the Breeze icon set not use some unexpected symbolism for the plain "download" icon. Or the other way around.

To summarize: plain "save" symbol just feels wrong with "download" icon name, does not meet developer expectations :) So please consider switching to sym-link "download" to "edit-download" instead.