[Prebuilt] HP Slim Desktop with AMD Athlon Silver 3050U, 8GB DDR4 (180$) [SurplusByDesign]

Yes, it's quite underpowered compared to Ryzen 3000's. The main advantage is that it only consumes 15W, which makes it very efficient to run, especially if you just want to a Plex server. However, if you want something more powerful (e.g. for transcoding, or other thread-intensive jobs), you can wait for the i3-10100 to go on sale (at around 200$), but you'd have to check it every morning.