Do you think that it’s becoming riskier to build off of open source code, from a trademark or IP protection standpoint?

Yes - to some extent. Programmers are resorting to generative AI's assistance, which might have accidentally copyrighted pieces of code (someone asked help on their code not realising it might be used for training). And same thing can happen through google etc. But there are bigger risks to worry about.

Protecting your own code is not worth it unless you are building a software product. Even then it can be extremely difficult and to win cases, even more so. Sometimes you benefit more by making it open source, so that others will improve your work.

I don't think so at all, especially for management software. The software is mainly made up of information organization and management logic. The code, often written badly, can help to understand the flows, but on its own it is only a non-relevant part of the applications.