It can be seen from your questions that you are a child who knows how to communicate. First of all, because you get good grades in math, it doesn't rule out that teachers have high expectations for you and don't understand your little mistakes, so they will criticize you. As for whether it is serious or not, it is difficult to judge because it involves perceptual knowledge. I suggest that you can talk to your teacher, which is what every good teacher is willing to accept. When I first started school, I sometimes had holiday syndrome. Not only you but also your teacher. If it really gives you pressure, it affects your study and communication!

Finally, it is very likely that after you communicate with the teacher, you will know what the teacher thinks outside of teaching and make you more mature. This may be your unexpected happiness!