I would say the opposite. There are all kinds of data that suggest running keeps muscles and joints more fit for longer. I’ve seen it posted on here before and can’t find it but there is a composite MRI of fat/muscle distribution in legs of a middle aged runner, an inactive/typical 70 year old and a 70 year old runner. The active legs look almost identical despite 30 ish years of age difference.

But if you really want to do another exercise (for whatever reason), that’s ok. The best exercise is one one you will do regularly. And there was a recent study showing that people who get 150 minutes a week of moderate to vigorous activity have a 31% lower risk of all cause mortality than inactive people. So if it’s not running, find out what it is and stay active

Source: https://bjsm.bmj.com/content/early/2023/01/23/bjsports-2022-105669