Возможно kde5-kcm-grub2 не виноват.

В changelog grub (grub/ChangeLog-2015) есть:

[...]
2010-10-12 Robert Millan <rmh@gnu.org>

    util/grub-mkconfig.in: Merge `GRUB_DISABLE_LINUX_RECOVERY' and
    `GRUB_DISABLE_NETBSD_RECOVERY' into a single `GRUB_DISABLE_RECOVERY'
    variable. All references updated.

    util/grub.d/10_kfreebsd.in: Support recovery boot entries.

[...]

А наш патч grub-2.04-os-alt.patch все еще полагается на содержимое GRUB_DISABLE_LINUX_RECOVERY.

Created attachment 12040 [details]
Патч заменяющий имя устаревшей переменной на новое

Просьба проверить исправит ли ситуацию замена в файле /etc/grub.d/10_linux

-GRUB_DISABLE_LINUX_RECOVERY
+GRUB_DISABLE_RECOVERY

Created attachment 12041 [details]
GRUB_DISABLE_RECOVERY

(Ответ для Николай Костригин на комментарий #2)
> Создано вложение 12040 [details] [подробности]
> Патч заменяющий имя устаревшей переменной на новое
> 
> Просьба проверить исправит ли ситуацию замена в файле /etc/grub.d/10_linux
> 
> -GRUB_DISABLE_LINUX_RECOVERY
> +GRUB_DISABLE_RECOVERY

Да, это помогло (заменила в одном месте в файле /etc/grub.d/10_linux).

grub-2.06-alt16 -> p10:

 Wed Sep 06 2023 Egor Ignatov <egori@altlinux> 2.06-alt16
 - 39_memtest: fix grub.cfg generation on i586 (closes: #47471)
 Tue Aug 22 2023 Egor Ignatov <egori@altlinux> 2.06-alt15
 - 39_memtest: add uefi support (closes: #47244)
 Wed Aug 16 2023 Egor Ignatov <egori@altlinux> 2.06-alt14
 - add f2fs, exfat, ntfs, ntfscomp modules to efi image (closes: #47257)
 Wed Jul 19 2023 Egor Ignatov <egori@altlinux> 2.06-alt13
 - change repo structure
  + get rid of git subtree
  + keep patches in a separate git branch
  + move alt-specific files to the 'altlinux' directory
 - post efi: probe quietly both efivars and efivarfs (closes: #46660)
 Fri Jun 23 2023 Egor Ignatov <egori@altlinux> 2.06-alt12
 - switch to the vendored gnulib of the required version
   + this makes it easier to port grub to other branches
 Fri Mar 24 2023 Egor Ignatov <egori@altlinux> 2.06-alt11
 - os-alt patch: change GRUB_VMLINUZ_SYMLINKS default behavior to yes (closes: #44406)
 - Introduced the grub-efi-checkinstall subpackage for automatic EFI
   signature verification (glebfm@)
 Tue Mar 14 2023 Egor Ignatov <egori@altlinux> 2.06-alt10
 - grub2-sysconfig: change default option to GRUB_VMLINUZ_SYMLINKS=yes (closes: #44406)
 - add upstream-0061-net-ip-Do-IP-fragment-maths-safely patch (fixes: CVE-2022-28733)
 - bump grub.altlinux SBAT level to 2 after closing CVE missed in the previous release
 Sun Jan 22 2023 Egor Ignatov <egori@altlinux> 2.06-alt9
 - fix os-alt patch: replace obsolete variable gone long ago (nickel@) (closes: #44387)
 - remove translation for 'Change language (press F2)' (closes: #45437)
 - remove rhboot SecureBoot patches; use upstream shim_lock and lockdown verifiers
 - update fedora-Rework-how-the-fdt-command-builds patch
 - add upstream security patch set 2022-06-07:
   (fixes: CVE-2021-3695, CVE-2021-3696, CVE-2021-3697, CVE-2022-28734)
   (fixes: CVE-2022-28734, CVE-2022-28735, CVE-2022-28736)
 - add upstream security patch set 2022-11-15:
   (fixes: CVE-2022-2601, CVE-2022-3775)
 - bump sbat global generation number from 1 to 3
 Mon Aug 15 2022 Nikolai Kostrigin <nickel@altlinux> 2.06-alt8
 - fix FTBFS with new gnulib (upstream patchset)
 - grub(-efi): switch from 'egrep' to 'grep -E' in filetriggers (closes: #43329)
 - update os-alt patch: switch from 'fgrep' to 'grep -F'
 - add alt-util-grub.d-switch-from-fgrep-to-grep-F patch