I don’t personally consider long tenure a problem, but if I were interviewing a candidate who had been in the same role, or even just worked at the same company

I don’t personally consider long tenure a problem, but if I were interviewing a candidate who had been in the same role, or even just worked at the same company, for more than 10 years or so, I’d ask them why they were entertaining a change. More generally, a long time ago I was advised to change up something about my job every two - three years — take on a new set of responsibilities, change teams, lead a community-of-interest group, etc. - to keep things fresh. I’ve found that to be good advice, both to avoid feeling like I’m not making any progress at work, and to avoid appearing to be unmotivated or inflexible. YMMV. * Edit - I guess I should add I’m currently a people manager and even as an individual contributor did a lot of interviewing. *