Beacons are way too low for the beams, the beam when looking in a beacon you can see visible
Fix: (Based on MCP 9.30)
TileEntityBeaconRenderer.java
public void renderTileEntityAt(TileEntityBeacon te, double x, double y, double z, float partialTicks, int destroyStage)
{
this.renderBeacon(x, y+0.19, z, (double)partialTicks, (double)te.shouldBeamRender(), te.getBeamSegments(), (double)te.getWorld().getTotalWorldTime());
//added y+0.19 to raise the beam
}
can confirm in 1.21.1