Upon using a specific Nether Portal, players on the server are being set on fire. This only occurs when travelling from the Overworld to the Nether. I had originally checked for any fire sources/lava sources near the portals on both sides but found nothing at any point above or below the portals. This is currently a big problem for members without fire protection who take much more damage and potentially die.

(After searching for other bugs there seems to be a lot about suffocation damage due to rounding but this is not the case. I also noticed another fire related bug marked as 'resolved' yet linked to a suffocation bug which did not help'.