The fruit that makes your mouth numb are Elderberry, Kiwi, Pineapple, Persimmons and even Sichuan pepper.
Sichuan pepper contains a compound that is called hydroxy-alpha-sanshool, which is known for it's numbing and tingling properties.
Elderberry contains tannins and some other compounds which can also contribute to and cause a numbing sensation in your mouth.
Kiwi fruit contains actinidin, which is an enzyme which can also cause a numbing effect and even tingling sensation when eaten.
Pineapple fruit contains bromelain, which is an enzyme which can break down proteins in your mouth and cause a numbing sensation or tingling feeling in the mouth.
And persimmons contain tannins, which can bind to the proteins in your mouth and cause an astringent feeling and numbness and possible tingling.
Not everyone will experience these numbing and tingling effects from these fruits.
Some people are more sensitive to these compounds in the fruits than others.
It's normal for some fruits to make your mouth numb or tingly feeling and someone else not experience the same thing.
It doesn't mean you're always allergic to these fruits unless it causes other symptoms like facial swelling, difficulty breathing, skin rashes etc.