I upgraded Reminders by mistake with Catalina. Can I go back?

Just upgraded my MBP to Catalina, because I didn't understand the warning about upgrading the Reminders app, I went ahead and upgraded on computer and now - eep! - it's unusable on my old iPhone. I really don't want to upgrade my phone over this - I only use it for reminders and maps. And TBH, the new reminders app takes a lot more attention (the lines jump re-sort themselves just as I'm going to work on it, and I can't just enter a time and have it understand - instead I have to confirm it all on another line, so it's tough to enter anything quickly).

Questions:

Is there any way to downgrade this, so it can sink between my MBP and computer again?

Is there a great alternate app for Reminders that will sync an older phone (6) and newer computer (2017 MBP)? I'm looking for something where I can enter "Call Joe 3:00", and have it know I want to be reminded at 3, without extra clicks or confirmations.

Thanks!!