Grub未加载最新内核：已安装的6.2.0-24-generic未出现在启动列表，已删除的旧内核仍显示

我最近更新系统后，发现最新的内核已经成功下载并安装了，但奇怪的是它们并没有出现在Grub的内核启动列表里，反而那些我已经删除的旧内核还留在列表中。我尝试了网上能找到的各种方法，比如执行update-grub2，但都没解决问题。

以下是执行sudo update-grub2的输出：

sudo update-grub2

Sourcing file `/etc/default/grub'

Sourcing file `/etc/default/grub.d/init-select.cfg'

Generating grub configuration file ...

Found linux image: /boot/vmlinuz-6.2.0-24-generic

Found initrd image: /boot/initrd.img-6.2.0-24-generic

Found linux image: /boot/vmlinuz-6.2.0-20-generic

Found initrd image: /boot/initrd.img-6.2.0-20-generic

Found memtest86+ 64bit EFI image: /boot/memtest86+x64.efi

Warning: os-prober will be executed to detect other bootable partitions.

Its output will be used to detect bootable binaries on them and create new boot entries.

Found Ubuntu 23.04 (23.04) on /dev/nvme0n1p3

Adding boot menu entry for UEFI Firmware Settings ...

这是ls -l /boot/的输出，能看到6.2.0-24-generic相关文件都存在：

ls -l /boot/

total 197696

-rw-r--r-- 1 root root   276283 Apr  6 08:33 config-6.2.0-20-generic

-rw-r--r-- 1 root root   275984 Jun 16 11:07 config-6.2.0-24-generic

drwxr-xr-x 3 root root     4096 Jan  1  1970 efi

drwxr-xr-x 5 root root     4096 Jun 29 17:45 grub

lrwxrwxrwx 1 root root       27 Jun 28 16:31 initrd.img -> initrd.img-6.2.0-24-generic

-rw-r--r-- 1 root root 77057438 Jun 17 13:05 initrd.img-6.2.0-20-generic

-rw-r--r-- 1 root root 79567659 Jun 28 16:31 initrd.img-6.2.0-24-generic

lrwxrwxrwx 1 root root       27 Jun 29 15:49 initrd.img.old -> initrd.img-6.2.0-20-generic

-rw-r--r-- 1 root root   138712 Feb 11 12:16 memtest86+ia32.bin

-rw-r--r-- 1 root root   139776 Feb 11 12:16 memtest86+ia32.efi

-rw-r--r-- 1 root root   144312 Feb 11 12:16 memtest86+x64.bin

-rw-r--r-- 1 root root   145408 Feb 11 12:16 memtest86+x64.efi

-rw------- 1 root root  8146863 Apr  6 08:33 System.map-6.2.0-20-generic

-rw------- 1 root root  8152253 Jun 16 11:07 System.map-6.2.0-24-generic

lrwxrwxrwx 1 root root       24 Jun 28 16:31 vmlinuz -> vmlinuz-6.2.0-24-generic

-rw------- 1 root root 14524456 Apr  6 08:35 vmlinuz-6.2.0-20-generic

-rw------- 1 root root 13854856 Jun 16 12:43 vmlinuz-6.2.0-24-generic

lrwxrwxrwx 1 root root       24 Jun 29 15:49 vmlinuz.old -> vmlinuz-6.2.0-20-generic

再看Grub的启动列表，那些已经被我删除的“oracle”和“lowlatency”内核还在显示，但明明存在于/boot目录且已安装的6.2.0-24-generic内核却不在Grub列表里。

备注：内容来源于stack exchange，提问作者uc100