Is there a reason why there can't also be a check for days since last gameban (EAC)? My server is for Rust so it's frustrating not to be able to check for the age of the gameban.

The plugin is based on steam profiles whose ban age response does not distinguish between VAN or gameban. DaysSinceLastBan contains the information being used here but its not documented in the steam api docs for ISteamUser/GetPlayerBans. So my best guess is that it refers to both types of bans and reflects the latest date.

Example response for https://api.steampowered.com/ISteamUser/GetPlayerBans/v1?key=<apikey>&steamids=<steamid>

{
  "players": [
    {
      "SteamId": "redacted",
      "CommunityBanned": false,
      "VACBanned": true,
      "NumberOfVACBans": 2,
      "DaysSinceLastBan": 269,
      "NumberOfGameBans": 2,
      "EconomyBan": "none"
    }
  ]
}​