You probably just don’t really know how to go about hiring a good agency - and how would you? Bubble skills and experience are completely different from any other traditional dev skills, and Bubble doesn’t give any measurable way to judge an agency’s ‘quality’. The tiers are essentially just measures of size.
You might find this guide useful: How To Hire A Bubble Developer
Freelancers have the problem (well, stereotype) of being a bit flaky and running off. Big agencies in Bubble tend to charge you $$$$ and outsource to a junior developer in Africa/South Asia and end up with a really tech debt heavy app.
I think it’s really rare that even a complex Bubble app needs more than one developer. One good senior developer and you’re good to go. As you add more, the senior dev spends more time cleaning up the work of the junior devs than they would just building it themselves. I’ve audited a lot of apps with in house teams/a few developers and haven’t found a single one that isn’t plagued with technical debt and bad build practices. I’ve audited equally complex apps built by one good developer that are in an infinitely better place.
Contract this out, you don’t need that many designs and design is pretty easy for anyone from a freelance platform to do with a quick brief.
The trouble with Bubble is that for the most part it handles poor optimisation well, so people overestimate their skill significantly and truly good senior devs are actually quite rare.