I just switched from Arch to Endeavour to Fedora! My 2 cents:
Arch is like a barebones Lego box without instructions, only a set of pictures. Sure, you get a paper telling you how to ensamble a basic OS, but what to do of it is up to you. For example, you might want a firewall there, right? or maybe a systemd timer to trim your ssd? IDK, you can guess it on your own. The pieces are there, it’s up to you to decide what to use.
Endeavour is like that same Lego box where someone handled you the manual from another themed box. If you installed Arch on your own, and felt like you might’ve missed something, or something feels off, EndeavourOS just gives you the ensambled set for you to play with. The problem? No problem, really. It feels like a greatly configured Arch installation.
Fedora feels like a themed box. You don’t have whole lot of bricks like that other unthemed box (AUR), but damn, everything just works and it works great. Only caveat is that non free stuff (drivers, codecs, etc) require that you input some commands (but really, every linux distro requires this still). So far, my experience is between “wow, I didn’t know you could do/have this! Must’ve missed it in the arch wiki” and “damn, there’s no easy way to install X in Fedora? I miss the AUR :(”
My brother in Christ, installing a .deb is downloading the .deb directly, as you would when downloading discord from discord.com, and you use dpkg to install it (apt uses dpkg to install the deb file).
You saying “the deb file” is not the same as “using the official repo”, as dependencies might not have been installed by only using the .deb file.
How do you handle which GPU is used in which game? I would guess you have an AMD iGPU, and a Nvidia GPU for games, right? Maybe something along those lines got updated?