Bidding for new shifts?!?

So I have been in my position for quite some time and suddenly we get an email that we all have to rebid for shifts and there is no seniority it’s based on metrics and attendance for the most part. So all the time just put in doesn’t count just numbers. Everyone will now work a 5 day work week despite having people having a 4 day work week now. And it’s either you work no weekends or every day of the weekend. This is such crap!!! My supervisor had no answers other than it’s all new to them too! I was hired for my specific position and now I may end up working every weekend !!! This is outrageous. Anyone have any other information about this.