The satellite image used by OSM is at least 5 years old - is there any reason for this and is it possible to get a more recent image as the background?
Reason is that they are free to use for OSM.
Newer images are available in commercial services that means if you want to invest a lot of money you can buy license for usage within OSM.
Not everywhere. Here the government released 2019 high quality aerial imagery, and some updates of lower quality were taken in march 2020.
For most locations, more than one set of images is available. In iD (the online editor on osm.org), you can switch between them with the layers icon on the right. Looks similar to this:
(Or you can press the “B” key.) There isn’t always a clear best option, as there may be a trade-off between how current the images are, the resolution, how correct the positions are, lack of clouds and leaves, …
Also, what’s available depends on what organizations owning such images have allowed us to use for mapping. We don’t have our own images.
Which set of satellite images are you looking at, and for what part of the world? Usually there are several to choose from. You can see them by editing the map in the browser and looking for Background settings on the right, or just hitting B should also work. For example for Ireland I can see Bing, two sets of ESRI imagery, two sets of Maxar imagery.
Edit: turns out I was typing while Tordanik was posting so I ended up basically repeating the same thing…