You could experiment further; instead of merely pressing Enter while on the Ubuntu, with Linux 5.4.0-llkd01 kernel's menu entry, ensure that this line is highlighted and press the e key (for edit). We shall now enter GRUB's edit screen, wherein we are free to change any value we like. Here's a screenshot after pressing the e key:
The screenshot has been taken after scrolling down a few lines; look carefully, you can spot the cursor (an underscore-like one, "_") at the very beginning of the third line from the bottom of the edit box. This is the crucial line; it starts with the suitably indented keyword linux. It specifies the list of kernel parameters being passed via the GRUB bootloader to the Linux kernel.
Try experimenting a bit here. As a simple example, delete the words quiet and splash from this entry, then press...
