I see 3 options that could've happened, although I only believe the 1 and 2 are plausible.
1. PK or Eevee donated, putting it in the name of "The Floraverse Community" because they knew that if they said their real (nick)names, the Twitch chat and Twitter would explode telling the organization that the donation came from a group of pedophiles who committed or supported children abuse. The "community" was a good way to dilute the guilt, yet getting what they wanted (to name one the kid after Neon).
This, however, makes me wonder how much are they earning. The last time we looked PK was getting around $960 for the normal floraverse, but we don't really know if they're getting money from other sources (other Patreon, allowances, govt support). That doesn't take away the option that they could've saved the money for a while.
2. They got help from a couple of their supporters, they put the rest of the money, and donated it in the name of "the community". After all, if people can finance them with almost $1000/month for doing nothing, they can perfectly get the same people to help them with some more to raise the 5K to have their character immortalized in a GDQ run.
3. The community did manage to get all that money together and donated it, although I really don't believe this is the case considering most of their fans are impressionable kids and young teenagers.
In the end the result is the same: $5000 went for Neon to be put on the game, they did it (I don't remember if the donation was read out loud, though), nobody thought about this, everything went on happily and nobody remembered the background behind the Floraverse community.