#21 shows it's been recently re-painted - wait for it - from the FAA to the ICAO standard? Hahaha. Just look at the picture. PAPI at 400 m and GS antenna at 330.
With 4 reds, the OP was below glide. That is not a good thing and was called properly, only using the wrong scale.
Being correct and 4 reds happens only on PAPI <> GP 150 m difference (had it on my last flight which we discussed, hence the keen interest today) and this was only 70 m.
Here:
(time stamp 2:50)