Is there any difference between A and B?
A: How the GRH movement led to acceptance of Ivermectin as a COVID-19 therapy in Peru?
B: How the GRH movement led to THE acceptance of Ivermectin as a COVID-19 therapy in Peru?
The definite article is used for specific things, so it depends whether you are speaking about a general acceptance of something, or a specific, formal act of acceptance.
For example:
He gained acceptance in the town.
This doesn't need an article because it doesn't point to anyone specific or any specific event.
He gained the acceptance of people in the town.
Because this refers to people, it is more specific - it is the people's acceptance, so the article seems appropriate.
In your example, I think it should have the definite article. Acceptance of a drug by medical authorities is certainly a specific decision made by a specific body of experts.