Career advice reg

I am on bench for last 6 months . On October I received the call from project for training . This training is for different tech stack . I have done the training and waiting for allocation since December. They asked to wait since the upcoming projects in pipeline. I am little bit scared of my bench period . Is it ok to leave here and join other company? If that's the case will they reduce the notice period? I am not getting enough project calls here. I have rejected many projects because of this project training. Is it good to change the tech stack after 5 years of experience. I can't handle the pressure .