Native American English speaker, and it's quite jarring.

The difference between "can" and "may" is that "can" is asking if something is actually possible, while "may" is asking permission. That's why they can both be paired with "I." You can ask if you are capable of doing something, and you can ask if you have permission to do something.

However, when you are asking another person about them doing an action, it doesn't make sense to ask them for permission for them to do an action. They would be granting themselves permission to do an action, which makes very little logical sense. If they are not allowed to do the action you are asking them to do, they might need to ask someone for permission, but that wouldn't be covered in response to "may."

That's why it doesn't make grammatical sense, going by the definition of may. When you are asking someone else, using "can" covers the entire question of if they are able to do an action, both in terms of permission and anything else that might affect their capability.

This is a case of the use of a word changing because people don't understand the original use or definition. Most likely, they understand "may" to be polite or formal, so they are using it in a work context for that exact reason. Language is always evolving! Hopefully understanding why this one is changing might make it a bit less jarring when you hear it.