There are a lot of false positives in this search but some look promising:
https://ww.wp.xz.cn/plugins/search/taxonomy+term+thumbnail+image/
The lack of updates or proper “tested up to” values doesn’t have to be a total deal breaker. If it is well written and does not add entries to your error log, it can continue to work properly for a good long while. I have a private plugin I created 8 years ago and it still works fine with no updates. Of course the risk is if it should end up having issues in the future it could be difficult to rectify. In other cases it may just take a simple code modification. The risk is more in the uncertainty than anything specific. Weigh against not having a better alternative. If the alternative is to not have category images, you can still do that if/when the plugin fails to work. And by then maybe there will be a better alternative.
