I think if you have been rejected by 3+ funders, where you hopefully got a good sense for why, you should seriously reconsider your project.
As Peter hints at below and which I’ve mentioned in another comment, the problem appears to be as soon as smaller donors receive info about a project having a funding application rejected by a more influential funder, such as the EA Grants, they reject them. So what some projects are experiencing isn’t the serial rejection of three independent funders, but rejection after it becomes common knowledge the first funder rejected them. The problem appears to be the funders with the most money or best affective reputation in EA are implicitly assumed to have the soundest approaches for assessing projects as well, which shouldn’t be the case.
As Peter hints at below and which I’ve mentioned in another comment, the problem appears to be as soon as smaller donors receive info about a project having a funding application rejected by a more influential funder, such as the EA Grants, they reject them. So what some projects are experiencing isn’t the serial rejection of three independent funders, but rejection after it becomes common knowledge the first funder rejected them. The problem appears to be the funders with the most money or best affective reputation in EA are implicitly assumed to have the soundest approaches for assessing projects as well, which shouldn’t be the case.