Everything my mom has saved to icloud is on my phone

Hello! My phone was recently stolen so I borrowed my moms phone and logged in to my apple id on her phone promptly logging out when I was done. I now have a new phone and when logging in all my mom's icloud save data is on my phone.

I read a community answer on here with a similar question stating, this is only possible if the same Apple ID was used when setting up both phones but they definitely weren't or if we share an Apple ID which we do not do either.

On her phone everything is as normal, she has no access to my passwords, photos, etc. Also under find my the phones are listed under the correct names. How do I get rid of my mom's icloud data without deleting my own? Thank you in advance for any help.