This is common practice in Germany, so it would not surprise me if that kind off stuff also reached the UN...
This is a treaty proposed by Russia, and heavily supported by the growing number of dictatorships around the world, such as China, the Arab states, and more recently the growing number of African countries, that will effectively allow them to prosecute anyone who says something bad about their countries under vague "terrorism" charges. If a western country refuses, then they can cut off any legal collaboration for any other more serious crimes. Example: UAE says this French national said something bad about their sheik. France must arrest and hand over that guy because they would be breaking an international treaty otherwise, and may be vulnerable to sanctions and UAE (and others refusal) to cooperate in France's legal investigations, such as economic fraud, terrorism, and such. It's basically a cleverly designed document to enforce and give more power to dictators across their borders, and inside other democratic countries.
[1] https://documents-dds-ny.un.org/doc/UNDOC/GEN/N19/383/43/PDF...
The main issues I see is that there is little distinction in what constitutes a crime that would fit under the "cybercrime" banner, potentially allowing a state that has e.g. anti-LGBT laws to request assistance in prosecuting that crime by e.g. getting de-anonymized data from a US-based social network.