Reviewers decline review invitations for various reasons. In most cases, they are either too busy with their work or they have already taken up other reviews. Since this is typically holiday season, many reviewers could be on leave. Another possible reason for declining a review could be if the reviewer is not very comfortable with the topic. However, generally speaking, reviewers’ refusal to review does not tell anything about the quality of a manuscript. So, I don’t think you need to worry about the editor having a negative impression about your paper just because three reviewers have declined the review invitation. This is not going to affect the editor’s decision in any way.