Don't think Jasper is anywhere near Mats.
Of course he isn't on the same level, otherwise he wouldn't accept a bench role, but he's not very far away. Anyway, what i wanted to point out is that if somehow Mats would get injured/suspended, we shouldn't be worried at all about his replacement.
We had two starter-material GKs when we had both Bravo and TS. Now talking about Cilessen, his passing might not be as good as Stegen's, but his interventions are great. And let's not forget Mats wasn't that solid not so long ago. Guy stepped up this season a lot (and the last months of the previous season too), grew in confidence, no more freezing on the goal line, and also had incredible saves.
Nowadays Ter Stegen is one of the best GKs in the world, but i think his starting spot could have been in trouble if we would be referring to his pre-2017 form.