Instances sporadically get a random username's timeline for RSS feeds
In #424, there have been reports of some Nitter instances returning RSS feeds of a random username (typically Japanese accounts) instead of the requested user. Unfortunately, those comments are beyond the scope of the first comment, although they are totally related to the same user timeline RSS endpoint, so I've decided to continue the discussion here to keep clean the issue mentioned earlier.

## Example observed behavior

The following is based on [this recent comment by me](https://github.com/zedeus/nitter/issues/424#issuecomment-901357852).

Say I add the RSS feed for [@loveliveevents](https://nitter.kavin.rocks/loveliveeevents) (an account whose tweets are posted in English) to my feed reader app on my PC. (I use Akregator on Manjaro KDE, if you're curious.) A few days later, I would suddenly get a notification saying I got 16 new items because the instance returned the most recent tweets from [some random Japanese user](https://nitter.kavin.rocks/nakiriayame) through the same [feed URL](https://nitter.kavin.rocks/loveliveevents). A few hours later, the instance gets the correct username's tweets again.

## Further details and where we're at so far

This bug has affected some, if not all, Nitter instances, particularly the [nitter.pussthecat.org](https://nitter.pussthecat.org) public instance. I've discovered this same exact behavior at [nitter.kavin.rocks](https://nitter.kavin.rocks) not long after creating this issue, but it went back to normal after [the instance owner restored service due to the server running low on storage space](https://github.com/zedeus/nitter/issues/424#issuecomment-901380315).

@PeterDaveHello has recently [set up a new Tor-only instance](https://github.com/zedeus/nitter/issues/424#issuecomment-900416176) to investigate this bug, and I will be on the lookout when my private instance or any of the public instances I use does the same. In the meantime, I'll be learning some Nim so that I can contribute code to this project.

CC @FireMasterK @TheFrenchGhosty @zedeus