Yeah, been experiencing the shady VC behavior more and more these days. Being upfront about not needing capital doesn't help as they continue to want to chat and contact you on every channel. Once you agree, it quickly turns into uncomfortable probing questions about financials and validation methods.
The reason becomes quite clear if you look at their portfolio. If there are companies like yours there, it makes a lot of sense as to why they want to know what's working with yours. They haven't invested in you, but they have in these other companies.
Almost every founder I've talked to has a story like this and warns against taking investor meetings/chats unless you're actively looking for funding and have done your research. Better yet, only follow through on warm introductions from other founders/people you know.