htaccess keeps on regenerating, impossible to rewrite

Hi, I’m facing a really weird issue.

I’m trying to optimize my htaccess file in order to make my website faster.

Thing is, I can’t get to write anything in the htaccess file. Every time I edit the htaccess file, it keeps on rolling back to a version from 22/04/2016.

I even tried deleting the htaccess file and uploading a new one with the extra data I want to implement, and even that way, after I refresh the data in Filezilla, I see the htaccess file has 22/04/2016 as the last edit date and only includes the original data.

Seems like something is controlling my htaccess, but I have no clue what it can be. I even tried to deactivate every single plugin and the same thing keeps on happening.

Any ideas on how to solve that ?

Thanks !