My 2001 RX300 AWD has about 10K miles.

Last week I happened to notice that the high beam lamps/bulbs seemed to be cloudy, a smoky grey film on the interior of the glass. So I bought replacement bulbs yesterday.

On removing the OEM bulbs I confirmed the interior of the bulb's glass enclosure is heavily covered with what appears to be soot, most likely from the bulbs operation at the low DRL voltage. In addition, there was a definite "bubble" in the glass immediately above the filament, likely due to heat buildup that the glass was not designed to withstand.

I went ahead and replaced the bulbs but at the same time I disconnected the DRL resistor under the battery on the chance that was the source of the "sooting" problem.