I don’t have a top tube bag from them but have a couple of other bags from Ojeva Negra and have thought about buying their Snack Pack. The stuff I have is really well built and wasn’t heinously expensive. They are a pretty small operation and are sometime out of things for a while but were really helpful when I gave them a call.
Worth thinking about exactly what you want the bag to carry. I’ve got one of the Revelate mag bags (no issues with it popping loose) and it is good for snacks but doesn’t really fit a cell phone and snacks or snacks and tools. My buddy has their Chuckbucket and it is pretty awesome for touring/rambling around the mountains but not so much for race day.
A half frame bag might be worth a look if you want to be able to carry more stuff and are less worried about easy access while riding.