Have had that happen in a couple of different states so far. Bone dry conditions. Different tunnel lighting each time. No idea what’s up. Annoying since it further smeared the windshield, the top third of which wasn’t getting cleaned to begin with.
Gremlins. Or suboptimal acceptance testing that failed to account for the tunnel use case.
Tangentially, tunnel differentiation is now gone as a result of the improved(?) maps package. That feature would now be (Navi)gon[e], as it were.