I live and work near to DFW airport. Yesterday, I noticed an inbound jet with obviously brighter strobes (anti-collision lights) than any other jet I've seen before. (I believe this was an American Airlines Jet with an engine under each wing.) Does anyone know if aircraft are being fitted with brighter anti-collision lights? This particular aircraft was really noticeable against the low overcast clouds.
Its possible they are just fresh halogen bulbs and brighter than others you have seen but your key line is:
against the low overcast clouds
Low clouds, fog, and the like give strobes something to reflect off of so they seem brighter in a localized way. I cant find a great image of it but this video showing the graphics updates in X-Plane 11 show the phenomenon fairly well. On a cloudless night the strobes (an most aircraft lights) have little to reflect off of so they seem darker when looking at them. If you watch departures and arrivals in similar conditions you will also see the landing light throw a similarly "visible" beam. This is all somewhat similar to how laser light is visible in fog.
LED aircraft lights can be (and usually are) made much brighter than incandescents due to the former's much lower power draw, so that may be what you're seeing. However, strobes are a bit more complicated than steady lights.
According to this analysis, the time-intensity product is 80cd-s for flashtubes and 200cd-s for LEDs. While the latter seems like 2.5x the light, the author notes several perceptual phenomena that may mean they're less noticeable in practice.
Small planes too. I plan to put brighter lights on my plane soon.
LED to replace the wingtip position (red/green) and strobe lights, and white on the tail. https://www.aircraftspruce.com/catalog/elpages/microburstIIIwhelen.php?gclid=EAIaIQobChMIxrLc876J4AIVibjACh0mCgigEAQYBCABEgJG_fD_BwE
LED landing light too https://www.aircraftspruce.com/catalog/elpages/whelenparplus36.php
Should be brighter, and use less current.
See and be seen!