Microphone not working

I noticed that while I record a Snapchat video my voice can be bearly heard like there is something covering the microphone. If I scream loud enough then something but little can be heard. I checked to see if same issue will happen while recording a video thru the phones camera app but everything seems to work fine. So I tries in different apps, Facebook worked fine, Instagram had same issue as Snapchat with no sound And even the voice recorder had the same issue. All call work fine while on speaker phone too. I tried rebooting my iPhone but the issue is still here. Did anyone encounters some or similar issue? I’m trying to find out if its issue with the phone or software.