iPhone Back up on XS Max

Hello my name is Emily. I recently had the IOS 13 beta from apples website, but it was lagging on my phone a lot. So, i removed it using iTunes on my laptop. Now, my phone is telling me it hasn’t been backed up in 2 weeks and when i try it tells me “the last backup could not be completed because ICloud contains a backup from a newer IOS version.” I’ve tried to back it up numerous times.