I faced this problem with my oneplus5 and now facing with oneplus7t as well.
This happens only for few apps.
Now iam facing this with YouTube....
I am using OnePlus devices from past few years I am getting lags on screen and also it also suddenly got struck currently IAM usingoneplus7t.
when IAM using apps like YouTube,pubg it was automatically getting closed
it is very irritating
fix this one as soon as possible
t mobiles offer available only in America or it is applicable to India also