Afghanistan–Pakistan border is a 2,670-kilometre (1,660 mi) international land border between the both countries that is called as The Durand Line. Although the Durand Line is internationally recognized as the western border of Pakistan, it remains largely unrecognized by Afghanistan.
There is a border barrier being built by Pakistan along with this Durand Line.
The cross-border attacks in Pakistan are carried out mainly by TTP (Tehrik-i-Taliban Pakistan ) , which is said to be the "ideological twin" of the Afghan Taliban who wants to establish their interpretation of Sharia - a hardline form of Islamic governance - in Pakistan.
The Aljazeera news article writes that
The number of cross-border terror attacks from Afghanistan has fallen
from 82 in 2019 to just 11 in 2020.
So there were just 11 cross border attacks in 2020 , which were fallen in numbers mainly due to the border fence.
After the Taliban takeover:
The TTP has claimed responsibility for over 70 terrorist attacks
in Pakistan since the US withdrawal, raising security fears that
led to both the New Zealand and England cricket teams cancelling
There is also a BBC article published on 13 October which gives us some numbers.
There has been a surge in violence this year, according to data compiled by the Pakistan Institute for Peace Studies (PIPS), an Islamabad-based research organisation.
According to PIPS data, the TTP carried out 95 attacks last year,
killing 140 people, and 44 attacks in the first six months of this
As the Afghan Taliban made rapid progress in Afghanistan and started
gaining control of various provinces from July onwards, the TTP
increased their activity. From July until September, the group carried
out another 44 attacks, claiming 73 lives. Those killed were mostly
members of Pakistan's law enforcement agencies.
So from July to September there were 44 cross border attacks in Pakistan since the Taliban takeover which is more than the numbers given by Aljazeera of 2020 which are just 11 and 82 in 2019. The TTP claimed 70 attacks since US withdrawal.
Judging from the numbers and the above graph we can say that cross-border terrorist attacks in Pakistan are increasing in numbers after the Taliban takeover of Afghanistan.
Image Source BBC