It sounds wrong because "since" is generally combined with a point in time, but "a few months" is a duration, not a date. Also the first paragraph switches tense forms, which makes it stand out even more.

Rewriting it to "since a few months ago" seems to be the easiest way to fix this, though my favorite way to express the the same thing is "as of a few months ago".

It should be noted that the author, like most people you're likely to interact with in this bubble, is not a native speaker of English. What matters is getting the message across - which they did.

You'll end up not being very productive if you spend your time pointing all of these little slips out.