XP Command Broken Syntax Error

Syntax Error Occurs with XP Command

What I expected to happen was...:
When using L following the experience amount, it should provide or remove xp in levels rather than points.

What actually happened was...:
When using L following the numeral the command fails with a syntax error.

Steps to Reproduce:

1. Enter a world with cheats enabled
2. Try command /xp 20L @s
   Notice it fails but is also listed as an autocomplete meaning the command should be available

Notes:

• Introduced in 1.16.0.63
• The same command but with points works fine