Summary:

If you put a space before the command (before forward slash "/"), the list of commands will still be displayed, but the command after entering will simply be displayed in the chat, and will not be executed.
This does not match the ability to enter multiple spaces within a command (as shown in this video). And also java version.
This greatly affects the copying of commands from the Internet, since all the time you need to pay attention to the space before the command, so as not to accidentally copy it.
And also since the list of commands appears, but the command after successful input does not work, I believe that this is not intentional. Any other character before the command prevents the command list from being displayed.

Steps to reproduce:

1. Enter a space in the chat.
2. Enter any command in the chat.
3. Send (Enter key) the command for execution.

Observed results:

The command was displayed in the chat, but is not being executed.
At the same time, when entering a command, a list of available commands is displayed.

Expected results:

The command will be executed.