Custom system settings lost after last upgrade

After last upgrade (few days ago) many system settings have been reset or lost.
Some applications were lost from “Autostart” list (Startup and shutdown section). That did not happen before.
Some custom shortcuts were lost (Shortcuts section)
My time adjustments were reset in “Energy saving” section (Power management).
(That were only some things that I’ve noticed hitherto.)

$ inxi
CPU: 6-Core Intel Core i7-8750H (-MT MCP-) speed/min/max: 800/800/4100 MHz Kernel: 5.10.59-1-MANJARO x86_64
Up: 1d 17h 18m Mem: 6736.5/15864.9 MiB (42.5%) Storage: 2.05 TiB (15.3% used) Procs: 355 Shell: Bash inxi: 3.3.06

That depends on the KDE team upstream…

If that doesn’t mean anything to you, please read this:

Especially the What’s this Upstream / Downstream business? section