Reentry

Your blue card may no longer be valid if your employment contract has ceased (as the employer would report this to Macau Police who would cancel your blue card).

Now since as you did not overstay your period of stay in Macau (i.e., have left Macau before your blue card expires), then there is unlikely anything preventing you from applying for a visa and subsequently a blue card again with a new employer. This is only to say that you have not violated immigration law. Whether you have violated local labor law is for the local government to decide.