Avastin treatment drug was changed to Mvasi, did this happen to you?

I started maintenance therapy with Avastin but it changed to
Mvasi (bevacizumab-awwb), it's biosimilar to Avastin, what I read online. They are similar but not the same. Do you know what " awwb" stands for. If you are taking Mvasi instead of Avastin, do you know the reason? Is it cost, availability or what?