Emoji notifications need to be consistent with the emoji in the client
Some of the emoji appear differently in notifications than they do in the client.
For example, the facepalm emoji appears in notifications as a woman facepalm emoji and then the female symbol. The sender does not assign a gender to the message, and could have inadvertently offended the recipient.
This can change the perceived meaning of the emoji. For emoji to work both the sender and the recipient need to have the same understanding of what the emoji means. The emoji typed in the client should map to the exact same emoji in notification and across platforms.
River Brandon commented
On macOS I see OS native emoji in notifications, and the much worse (IMO) app-specific emoji in Teams. Just fix this by using OS native emoji everywhere, and supporting the full unicode set. Done.