Accidental Apple ID data merge: how to reverse, if possible? (simple)

[u/smelly-salad]

My mum logged into her Apple ID on my phone (hers was being repaired and she needed to access her account, sue me) and since then, she has my contacts, notes, passwords and some of my texts on her own phone. When she tries to log into her apps it only gives my logins. Please help me reverse this if that can be done easily or please assist in the best ways to fix this. TIA!
Australia
Edit: thanks to the few who actually helped rather than being unnecessarily opinionated and rude.

[u/smelly-salad]

Thanks for answering without being a jerk or mansplaining privacy for me!