Any ideas of what could be causing my taillight to flood?

I have an 04 Lexus rx. This left taillight was replaced in May 2023 for the same water issue. My mechanic and I both thought the new one would solve the issue. The last few months this new one has been doing the same thing. Since it’s winter it’s freezing and having a hard time clearing out. Is there some sort of weather stripping that could be messed up? This car has been awesome so I’m hoping it’s not a huge fix. Any ideas of what to look for are appreciated