You already know why you should pick Debian:

Pro: The most stable OS I’ve used

About your "ancient packages" that's an easy fix, just install all your software using Flatpak/Flathub and you'll get the latest software on your rock solid base system.

I’m using EndeavourOS and I use DaVinci Resolve. The only issue I’ve had is a strange bug in DaVinci 18.6.x where my footage will start flickering after a few minutes.

I shoot in SLOG3. The flickering looks like my colour grade flashing on and off for a frame or two. It will persist until I turn off all of my colour nodes, save and quit, open Resolve again, and turn on the nodes again.

I haven’t figured out what is causing it yet.

Gotta throw my vote in for tumbleweed. Its IMO the best distro to get the latest packages while still maintaining stability. Their built in roll back feature is great.

Software not being well supported is kinda a sticking point. Though honestly its becoming less and less of an issue each day. Flatpaks are available for almost everything, distrobox covers the rest. I really haven't run into any situation that prevented me from doing what I wanted. I've been using it for a few years now across my desktop, laptop, and my computer at work. Suse is enterprise Linux after all, its still got great support

If you are interested in something arch-based but like having guis for stuff, I highly recommend Garuda Linux. I've been using it for about a year on my everyday desktop for gaming and it's been great. I also have really liked fedora bazzite on my laptop for almost the same time period.

I'd stay away from manjaro, I wouldn't touch it again with a 10 foot pole. Every time I've tried to use it, it just breaks itself every 3-6 months. I know some people swear by it, but I just have to assume they either have extreme tier knowledge to prevent trouble before it starts, are so used to fixing problems they are blind to their time spent doing it, or they are just incredibly lucky.

If you are using davinci on your system a lot, you can try their pre-packaged iso. They recommend rocky Linux nowadays and also provide an iso for it.

I wouldn't recommend any of those. Since you have Nvidia go with Linux Mint or Pop os as they both have good support for Nvidia.

I was once in the same boat. Here is what I did, put a second drive into my PC and separated my root and home partitions then kept hopping distros until I found the one that worked for me. That way, I didn't lose my important files while hopping. The distro I landed on was endeavour OS. I have been using it for 3 years now. Not suggesting that you should use it, because every distro works differently for different people depending on many factors. But try this and see if you find your own endeavour OS. Good luck :)

Cannot say for other programs you mentioned (although I'm sure they work fine as well) I'm using Godot on EndeavourOS and it is perfect. If your only concern is terminal, EndeavourOS has built-in scripts for updating your system. Also using an AUR helper would make your tasks easier, which "yay" is pre-installed. You can basically type "yay package_name" and it will guide you.

I use Opensuse leap. It works for me. If i cant find software i want i use the nix package manager

Mint DE. Enable backports or whatever if you want to. Get a newer kernel. I'm on 6.1

debian stable with backports and flatpaks will get you up to date software and a very stable base

you want debian and snaps/flatpacks/appimages/containers or whatever for the stuff that's not in backports or needs to be updated too frequently (yt-dlp).

when i left slackware i tried all the distros, and had all the complaints you have about debian. why should i have to deal with an out of date package when slackware let me convert rpms to tgzs and install them willy-nilly? turns out i can do that with debian just fine.

walk that road though, you gotta travel far to get home.