SUMMARY
I noticed that plasma startup not as fast as could be. So I decided to strace it and found that during plasma startup I have tons of this:
access("plasma/desktoptheme/default/translucent/colors", F_OK) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/home/vova7890/.local/share/plasma/desktoptheme/default/translucent/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/home/vova7890/.local/share/flatpak/exports/share/plasma/desktoptheme/default/translucent/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/var/lib/flatpak/exports/share/plasma/desktoptheme/default/translucent/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/usr/local/share/plasma/desktoptheme/default/translucent/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/usr/share/plasma/desktoptheme/default/translucent/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
access("plasma/desktoptheme/default/colors", F_OK) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/home/vova7890/.local/share/plasma/desktoptheme/default/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/home/vova7890/.local/share/flatpak/exports/share/plasma/desktoptheme/default/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/var/lib/flatpak/exports/share/plasma/desktoptheme/default/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/usr/local/share/plasma/desktoptheme/default/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)
statx(AT_FDCWD, "/usr/share/plasma/desktoptheme/default/colors", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT, STATX_ALL, 0x7ffcf304a550) = -1 ENOENT (No such file or directory)

Checked also on neon unstable - I don't see such paths anywhere.

$ grep -c 'plasma/desktoptheme/default/translucent/colors' plasma-file-access.log 
109200

STEPS TO REPRODUCE
1. Start plasmashell with strace
2. Observe many tries to access not existing files

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.3.2
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2
Kernel Version: 6.13.6-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 9950X 16-Core Processor
Memory: 94.0 GiB of RAM
Graphics Processor: AMD Radeon RX 7900 XT
Manufacturer: ASUS