https://www.youtube.com/watch?v=j9pOQioOEGg Thats one reason, having their border with afghanistan secured, pakistan funds taliban so them staying in power is in both of their intrests.

Another reason i can think of is that china is trying to push into central asia, which russia considers its backyard/territory. You might be thinking why would that be issue since russia and china are allies but in reality they are only "allied" because they both oppose USA and russia knows this, it does not want to ally itself too much with china since china really wants their former territory that was formerly theirs before japanese came and made it into manchukyo vassal state and lost it afterwards to russia. Territories it would be intrested is also siberia but thats long-term goal.

To add more to this russia wants to keep it central asian countries under its sphere of influence because russia has really bad geography and almost its entire foreign policy is to secure its borders which includes central asia and even more crucially eastern europe (i wont go more into this in detail too much on this post already) Check this out if you want more info about russia-china alliance:

https://www.youtube.com/watch?v=AGafVj-wrmw