Version 12.1.1 unable to type ">"

That is a known bug in 12.1.1. WRI is going to publish a new build.

Issue and workaround see here:

https://community.wolfram.com/groups/-/m/t/2006722

Disabling spell checking helps in the mean time:

Preferences 
> Interface > Check spelling as you type


Open menu Format > Edit Stylesheet... and paste this below the "Inheriting base definitions from" cell:

Cell[StyleData["Input"], StyleKeyMapping -> {}]

Choose Yes when prompted to "interpret the text" then close the Private Style Definitions Notebook.

This should remove these automatic Cell conversions from Input cells for the working Notebook.

You can save the Private Style Definitions Notebook and define it as the new default stylesheet to make this change persist.

---

If you wish to preserve this functionality but make its entry less accident-prone consider this instead, used as above:

Cell[StyleData["Input"], 
  StyleKeyMapping -> {
   KeyEvent["=", Modifiers -> {Control}] -> "WolframAlphaShort", 
   KeyEvent["*", Modifiers -> {Control}] -> "Item", 
   KeyEvent[">", Modifiers -> {Control}] -> "ExternalLanguageDefault"
  }
]

Now you will need to hold Ctrl as you type the character =, *, or > to enter each of these Cell types.