Opening Links from some applications takes a long time

I was having the same issue until I found a solution. Whenever I tried to click a link in Slack, the logs in journalctl -f showed:

xdg-desktop-portal-kde[1886]: xdp-kde-settings: Read called with parameters:
xdg-desktop-portal-kde[1886]: xdp-kde-settings:     group:  "org.kde.kdeglobals.General"
xdg-desktop-portal-kde[1886]: xdp-kde-settings:     key:  "menuFont"
xdg-desktop-portal-kde[1886]: xdp-kde-settings: Key  "menuFont"  doesn't exist"

It turns out I was missing some values in my .config/kdeglobals configuration file, as the error above shows. You can regenerate the missing values by going to System Configuration -> Fonts -> Do any random change -> Apply.

After doing this the links started working fine.

When opened with affected apps (i.e. Slack) it hangs on "kde-open5 https://some-url" (which is launched by xdg-open).

I've tried to debug this with strace:

mv /usr/bin/kde-open5 /usr/bin/kde-open5.orig

Then created an executable (chmod 755) /usr/bin/kde-open5 with the following content:

#!/bin/bash

strace -f -s 1000 -tt /usr/bin/kde-open5.orig $@ &>/tmp/kde-open5-$RANDOM.log

And seeing where exactly it hangs.

I think it deserves its own Launchpad ticket?