

There is a bug that is open right now which sounds like it might be one you were experiencing or possibly explains part of the issues.
https://bugs.kde.org/show_bug.cgi?id=501073
Like the web browsing might have been from middle clicking, which causes a lengthy hang and resuming from suspend and powerdevil are a prime suspect for it.
The login wait might be an issue I vaguely recall about the splash screen and that disabling it removed the startup hang.
I’ve been exclusively using Manjaro KDE since September of 2021 and the linked issue I started getting a couple months ago and it’s gotten bad enough to make me want to start hopping again.
Yeah this is important to know as installing two DE’s can and will cause a lot of problems.
I’ve read, but have not tried, that installing each DE under it’s own user can prevent the majority of these problems. This also prevents using apps from different DE’s simultaneously, you have to switch users to do so. Session saving makes it faster than restarting constantly but it can still interrupt workflow. Again, I have not tried this myself but have considered trying it.