The 'appstore' of some distributions, e.g. Linux Mint, displays a warning or hint for unofficial flatpaks. In Mint the display of unofficial flatpaks are toggled off by default and there is a warning or recommendation displayed against toggling on.

Seconded. I use Debian with KDE btw ;-)

Windows -> Ubuntu 10.04 ... 11.10, -> Kubuntu 12.04 -> Debian 7 (stable)... 8 (testing... stable) ... 12

Yes, usual releases are supported ~ 3 months, LTS versions get support for a much longer period e.g. 6.6 for 3 y, 6.1 for 4 y, 5.15 for 5 y or 5.10 for 6 y.

Two different things. LTS kernels get security patches until their support is dropped.

Yes, but if e.g. openSuSE installs its Grub 2 on top of Ubuntu's Grub 2, you end up with a different theming. If Windows overwrites the bootloader, the Linux boot options are gone.

No, but somebody else has done it and it is basically like the standard procedure for switching between releases.

It ain't much, but it's honest work.

3. There's a Dropbox .deb and .rpm for linux as far as I can tell, but I cannot attest to its quality or how well it integrates with a given file manager. Cloud accounts are generally well supported amongst the key desktop environments, for which I'd consider Cinnamon to be a part of.

In 2018 Dropbox dropped support for running/syncing on encrypted partitions, in my case ext4 on encfs. Don't ask me why.

I don't know if that's still the case.

If you are using Xubuntu 22.04, it should be possible to switch without reinstallation, as Linux Mint and Ubuntu are binary compatible as Mint uses Ubuntu's repos and only adds Mint-specific packages in its own repo.

As there are LTS branches, currently 5.4, 5.10, 5.15, 6.1 and 6.6 which will get updates until Decembre 2025/2026, I don't see the problem.

I guess, the governor is set to performance for a realtime kernel to work properly, thus the CPU consumes more power.