You should probably have read the respective update announcement, and most of the issues you describe might have been avoided.
This is the relevant note from the Stable Update 2024-05-13 Announcement, originally: If you use KDE you better logout of your session and do the update via Pacman or Pamac in tty.
Search the forum (you did that, right?) and you’ll find many examples of others not taking the necessary precautions; and additionally, a few ways to recover from the situation. See the link at the top of this post for a general procedure.
Latte Dock is not supported in Plasma 6. I used it myself for a while; sad to see it go; that’s life, move on.
Cheers.