What is the best way to start applications minimized?

So far I have tried to use Window Rules in the settings but that option seems to be completely useless since it does not work (tried it on KDE neon 5.22 with Plasma 5.22.4 and Kubuntu 21.04 with Plasma 5.21.4).

Then I found I can use kstart, e.g. "kstart5 --iconify kwrite". The problem is that I can't get it to work with flatpak and snap packages.

Is there a way to solve this using the methods I tried or is there some other better way?

I tried using the Window Rules in KDE settings to start the applications minimized (using minimized=true option). Unfortunately, this doesn't work either. Are there any other ways to try to solve this?

I could be wrong and it depends really what you call minimized. Some apps have that option in their settings. But, isn't there something like startintray?
Maybe something like: /snap/bin/whatever-desktop -startintray -- %u

Funny, I do have exactly the same issue since some time.

I think it's kind of a bug, because minimizing an Application-Window via right mouse-click at the Window-Header & choosing `Window-Settings for this Application` => minimize at initialization = YES didn't work for any Application at all.
BUT it works if you choose "execute now".

So I think we should fill a Bug-Issue for this?!?

I tried it too. Adding rules in system settings>windows>window rules>add minimized rule. Doesn't work.

Hmm. I think I found it. System settings>window stuff>window rules>add new>detect window property>window class>regular expression. It's regular expression that did the trick. But, that solves it for one application at a time. I have no idea how to set the rule for every application in one go.