Here, I will say a little bit of the opposite: when Bangladesh wins the first two matches and leaves the entire series with one match left, they gain such confidence that they want to win the third match without having to perform. I hope you understand what I really mean.
We have seen such performances from the Bangladesh team in most of the previous series that if they win the first two matches, they lose the third match. And besides, since it's already a very difficult match for the Bangladesh team, they won two matches, even if it was just to catch their breath, and they could lose today's match.

Yes, there are many records that Bangladesh won two consecutive matches but lost the third match.
However, Bangladesh won the toss and decided to bowl. We can see a change in the Bangladesh team's XI, Tanzim Hasan Sakib has been given a chance instead of Mustafizur. Since the match is not important for Bangladesh, maybe Mustafizur was not kept in this match.
Now if Bangladesh wants to win, then Afghanistan will have to be restricted to 150 runs, but if Afghanistan scores 165-175 runs, then it will be very difficult for Bangladesh to chase. Now let's see how many runs Afghanistan can set a target.