I had a bunch of Pi 3Bs sitting around, so I made piholes for a few friends and family, I made a dedicated MAME emulator that I never have time to play, and I gave one to each of my kids to learn about computers and linux. I also use one for work as a linux test environment for our software, but the 3 hardware doesn't really keep up.
Since none of these require a Raspberry Pi to run, I would suggest using a mini PC (with an Intel N100 or similar) instead of a Pi 5. With all the accessories needed for the Pi, a mini PC can actually be cheaper and of course a lot more powerful. Since the Pi 5 is very power-inefficient, a mini PC can even be better in that regard too if that matters to you.
Especially for Jellyfin a PC with an Intel CPU with integrated GPU is awesome, since Jellyfin supports hardware transcoding with that.
Compared to other SBCs, Raspberry Pis have been pretty inefficient for a while. A Pi 5 idles at about 3 W, which is pretty terrible for such a board, compared to other similar devices. You can get X86 PCs that idle at 3 W which are way more powerful. Other ARM SBCs use less than half that at idle and similarly less under load.
There are probably multiple reasons for that. The Pi's SoCs have always used rather old process nodes, which are more power hungry than more modern ones used by other single board computers and PCs - 16 nm for the Pi 5 SoC and 28 nm for the Pi 4. Also, with the Pi 5 there is this additional "south bridge" chip which is attached via PCIe. This consumes additional power and for some reason the PCIe link is configured such that it never enters power saving states. I don't know why.
Also, the power supply circuitry on the Pi 5 is far from ideal with its 5 V / 5 A power supply. Such a low voltage at such a high current can easily cause additional losses on the wire. That's mostly relevant under high load though.