Firefox – Open Containing Folder with wrong file manager

Hi, I have a problem with opening containing folder in Firefox Downloads section. I set Dolphin as default file manager with Plasma 5.20.4.
If I go to Downloads section and then I click to the right of the file name (on the folder icon), the downloads folder opens with Thunar.
If I go to Downloads section and then I click to Show All Downloads", a nd then I click to the right of the file name (on the folder icon), the downloads folder opens with Thunar.
Strangely though if I go to Downloads section and then I click on Show Downloads Folder", the downloads folder opens with Dolphin.

I already tried many solutions, but none of these is working. Here is some information about my configuration:

Inside ~/.config/mimeapps.list, ~/.local/share/applications/mimeapps.list and ~/.local/share/applications/mimeinfo.cache I have this line:

inode/directory=org.kde.dolphin.desktop;

If I run the command xdg-mime query default inode/directory" I get this: org.kde.dolphin.desktop

The only way to exclude Thunar is to rename /usr/bin/thunar.

How can I solve this problem?

Thanks in advance,

Scorpion77