2024 Subaru WRX — brake fluid is old but still looks clean

I wouldn't throw parts yet. Swap the cheap/easy piece first on the 2024 Subaru WRX and see if the fault moves. If the cheap test changes it, stop and reassess. Do that first. I'm in no rush to be a hero on it.

I'd want a measurement, not a hunch. If a shop can't duplicate it on the 2024 Subaru WRX, bring a video plus freeze-frame data, not just a story. That's the branch I'd chase this week. That's the sequence I'd use. I'd sleep better after that step, even if it finds nothing. Trying not to diagnose from the couch.

I went back under the 2024 Subaru WRX and it only happens after a heat soak, not on a cold start. If it repeats twice more I'll book time.

Ask what changed right before it started. Get a real battery/charging test on the 2024 Subaru WRX, not just resting voltage, before blaming a module. You'll know quickly if you're on the wrong tree. If they can't show the line item, I assume it's hiding. Checking again after work.

Log the conditions before you spend. If a shop can't duplicate it on the 2024 Subaru WRX, bring a video plus freeze-frame data, not just a story. That's the branch I'd chase this week. On “brake fluid is old but still looks,” that was the fork that mattered for me. Write the result down so the next test isn't a repeat of the last one. Happens in gear, not in park, for what that's worth.