25 people on the team, and under $300K ARR? That sounds completely unsustainable without either more growth or a much smaller team, so staying there definitely sounds dicey.
That being said, ask your attorney about non-competes and IP before making any moves. If you do your own thing, draw extremely clear lines to be sure you started from scratch and took nothing from your current company. No code, no docs, no contact info for customers, nothing.
I would also suggest to not start anything right away. When I've been in situations where I thought I could do more with a product than the current team, and then spent 6 months away from it to clear my mind and look at bigger pictures... I have yet to actually want to go back to a prior problem space. More often, I just close the chapter and find something new. In short, be wary about following what you happen to be doing today vs. what you truly care about.
Don’t bother with the lawyer.
It’s nearly guaranteed that this new idea fails as bad as the one they’re working at now. Why spend $500 to be told “don’t do it” which is basically what a lawyer is going to tell you if you give them only $500.
If somehow against all odds, this person’s implementation becomes a seriously successful business, they’ll figure it out then.