Disabling paste is usually done in the name of security.

For example, let’s say the user has to type their email address twice. Using 2 separate inputs means a mismatch can be caught. But that doesn’t work if they paste an error from the first input into the second.

But disabling paste degrades UX and is a terrible way to stop users from making mistakes.

Here’s why:

Problem #1: It makes the interface feel broken

This is because users expect to be able to paste but instead it just gets ignored with no feedback.

Problem #2: It slows users down

This is because the user has to type everything again from scratch.

Problem #3: It increases the chance of error

This is because typing manually increases the chance of a mistake.

Give users control and let them check their answers

The way you do this will be different depending on what the user is trying to do.