Send us your app and a bit of context. We'll look it over and send back a short video with what we'd check first, what might be causing the problem, and what we'd do next.
For context: we're a Gold Bubble Partner that regularly works on Bubble apps with $10 mil+ funding and 100k+ users, where tech debt or performance issues are getting in the way.
As a Bubble partner agency, we can bypass collaborator limits on your app plan.