When you start a new job, the work is usually already in full swing and there is a lot to learn. Often the way certain things are done will seem odd or contradict your previous experience. There is usually a good reason for the choices they have made, so ask polite questions, try to understand the reasoning and in general go with the existing flow.
However, sometimes your external view can bring an important insight. Perhaps there is a tool from another industry which they don’t know about. Perhaps the person who made the weird design choice was working outside their comfort zone. Perhaps the design evolved from a lab prototype without anyone taking a step back and designing it as a product.
If you do make suggestions, be polite and don’t be disheartened if they are not implemented immediately. By definition most teams hire new staff when they have more work than they can cope with.