How to downgrade to 13 from 14?

Ever since i updated my phone, a few very important apps stopped working. I can’t work and I need a way to get the old app to be installed on the phone.
any ideas how?

cheers

Hi
thanks for replying. I have tried installing the APK it just won’t install on my s24. And i have contacted the app developer and there is no reply as well. I didn’t want to hack my phone because I would lose warranty. So no matter what I tried it stopped working