While looking into this, it turns out it happens all the time and many websites have been blocked for years. If you're big enough then maybe you can get unblocked. Or you might just be SOL.
Some examples:
https://www.alexa.com/ has been blocked for over 1 year (https://www.reddit.com/r/india/comments/b084so/why_alexacom_...) (wtf?)
Trinet.com, an HR tech+services company is blocked in India (wtf?)
Adobe-owned behance.net is blocked in India. (why?)
reddit.com or parts of it are frequently blocked/unblocked https://thenextweb.com/apps/2019/03/14/isps-are-reportedly-b...
9gag and collegehumor have been blocked for over 5 years (https://www.news18.com/news/buzz/comedy-websites-colleghumor...). At least there's some reason here.
Three environmentalist websites were blocked (and eventually unblocked): https://scroll.in/latest/967589/centre-run-agency-blocks-web...
The NYTimes was blocked for a while: https://gadgets.ndtv.com/internet/news/new-york-times-access...
In 2014, India blocked Github for a while: https://qz.com/india/319866/a-threat-from-isis-prompts-india...
India is known for filtering websites belonging to NGOs, feminist groups, and others https://indianexpress.com/article/india/india-tops-list-of-w...
As far as I can tell, if there's some random bureaucrat that doesn't like you, your website is going to get blocked. Equally likely, the process is so poor that you might get blocked for no reason at all.