And it’s not the Subaru!
I think the Tacoma has a leaking headgasket. I’ve read the 2005 and early 2006 had a weaker design. Toyota changed part numbers mid-2006.
During Highway driving the coolant overflow fills up and spills over. Sitting in the driveway after getting home the overflow bottle is ‘bubbling’ with air bubbles coming out of the line from the rad. Engine temps stay normal (~90c on the scangauge) otherwise truck runs fine - no codes - no issues. I’ve replaced the rad cap hoping it was the problem but it didn’t help.
Once the engine cools down the coolant goes back into the system and the overflow tank goes back to normal levels. Around town driving is fine, no misfire or anything.