The term “Mother of God” is a loose translation of the term, “Theotokos” — God-bearer.
It is more a statement about the One who was in her womb (the Son, who was both fully man and fully God) than it is about herself (no one believes that she is, say, the source of God Himself).
I will add, of course, that whenever I read threads like this one or see the term “Theotokos/Mother of God” used in a way that is meant to cast glory onto Mary, I am reminded of Luke 11:27 - 28.
Any honor due Mary has less to do with whether she physically bore our Lord and more to do with whether she listened to the word of God and obeyed it. I personally believe she did so in a manner worthy of the highest praise... but, as I am not Catholic, I believe this is a point best left to Christian liberty rather than an essential point of that gospel that saves souls.