Email Verification Code Is The Same For Multiple Accounts

I’ve gotten complaints from my client that the email Verification code sent to verify vendors registration is the same. The same code is shared. I made research of my own, registered with multiple accounts and got the same behaviour. Isn’t the code generated supposed to be random? Why are the same codes getting reused by multiple accounts. It makes no sense security wise.

If there is a way of making this verification code random, it’d be appreciated. Thanks.