Mature and seasoned professional
This actually isn't something that I personally feel is a red flag but when I was doing research for this article, I found that this came up a lot. Conversely, "young" and "energetic" is also frowned upon by a lot of people. The notion here is that you're giving people a reason to immediately bucket you into a group that actually might have a negative reaction than a positive one. "Mature" could imply that you're stuck in your ways and too old to change. Personally, I think the digital industry should have a few more seasoned folks in their ranks, but this is a huge "no-no" listed by many hiring professionals so I would avoid it.