I think it has to do with the system updates. I use tecno too, and i always install all the updates.
My Instagram would uninstall its self after I restart my phone. My Snapchat won't open, it would always "stop". I thought the problem was from the apps so I uninstalled and reinstalled them, but nothing. I waited for the next app update and updated the apps. Still nothing. It wasn't just Instagram and Snapchat. There were others. I started to think that the problem was from the phone, so i waited for its next update. And i installed it. No change. It only got worse as i kept installing their updates. I found out that, as time goes on and we keep updating our phones, it kind of downgrades the phone, and we unknowingly install a virus put in these updates .Because the phones company wants us to upgrade to a new one. By that I mean, they want us to buy a new one. Its all business. I heard this from someone, I don't know how true this is. But then I did a factory data reset on my phone, and everything is back to normal.