Background: the key+IV define a keystream which is xor-ed against the message. The same key+IV generate the same keystream. Thus you can XOR two cipher texts and reveal information from the two plaintext.

AES-GCM is authenticated encryption. To combat known-ciphertext-attacks, you want to have authenticated cipher texts. AES-GCM specifically is vulnerable to an attack with a reused IV to recover the authentication key. Allowing you to forge authentication tags and employ a KCA.

The solution, if you're stuck with aes, is to switch to XAES-GCM or better AES-GCM-SIV. Alternatively you must use a counter or checkes system to not reuse IV. Since this is in the context of 1fps, you could use unix timestamp + random bytes to reduce the chance of collisions.