I am not the only person with this issue as I found this video on youtube perfectly showing the problem I am having.
https://www.youtube.com/watch?v=0S-VKAHUNWw
I installed endeavour OS fresh 2 days ago, I used the brave / chromium bin install from the AUR.
Both Chromium and Brave will not let me download any files, the video shows the problem I am having perfectly.
I know this is not the solution you are looking for, but to bypass the bug for the meantime you can use flatpak for chromium and brave.
Since the bug is on the aur build, check aur page comments there might be a fix someone posted.
Also, Chromium is available from extra repository. No need to use chromium-bin AUR package. See https://archlinux.org/packages/extra/x86_64/chromium/
Apologies, chromium was from extra, brave-bin from AUR, I am now trying brave from AUR,
Any update on this? Any other users seeing this issue?
Is it only endeavour an OS issue?
Can anyone else replicate this? I assume if there are youtube videos on it its not just the two of us?
sounds like this person has a similar issue:
Thats not the place to report application BUGS 
EndeavourOS do not maintain or ship Brave nor Chromium.
From a first look it looks like the window it opens to save the file is instead the window to open files…
Just tested it on chromium in KDE. Webpage saved just fine. Maybe a permissions issue? Maybe the package was installed incorrectly somehow?
yea fresh kde install installed brave-bin and chromium no issue here saving downloaded files or created pdf output into users home dir…
Could be add-ons extensions in the browsers?
Is it the same with firefox ? can you save files in home from any other app?
users dir permissions?
ls -l ~/
could be /tmp is full?
duf
2nd Fresh installed fixed the problem
