Short answer, COVID-19.
First, COVID shut down a lot of development for a long time and we're just now getting back up to speed. So rather than trash all the work on these previous gen games, it makes more sense to scale them up and make current gen versions as well, with more bells and whistles, like VRR, 120hz modes, Ray-tracing, higher LOD, and shorter loadtimes. And honestly, I'm fine with this. I'm loving the bells and whistles. I'm loving the fact that I don't have to deal with dogshit framerates in the 20s anymore, and dynamic resolutions that drop below 1080p, and minute and a half load times. This in-between time is giving studios time to develop their skills with the new consoles, such that once we're fully into the current gen, they should be pumping out some super impressive stuff.
Second, COVID shut down a lot of hardware manufacturing, which again is just now starting to get back to normal. So that means there's fewer current gen consoles out there and many are still in the hands of scalpers. Thus, the audience for current gen games is smaller than a normal gaming generation, which means financially, it doesn't make a lot of sense right now to limit your sales to just PS5 and XSeries consoles. But, with chip shortages seemingly starting to clear up now, given the price drops in graphic cards, we should rounding the bend on this issue.
Third, international supply chains are fucked, with massive shipping containers sitting in ports for days and weeks longer than normal or getting re-routed from one port to another, which again means gaming companies can't get their product to end users fast enough. For example, I read an article about the US shipping industry recently. The Los Angeles seaports are so backed up, they're re-routing things to the Savannah, GA and New York ports, which are also backed up and which are on the whole other side of the country. So again, if end users don't have PS5s and XSeries consoles, it makes no sense to develop exclusives for those platforms.
Generally, the pandemic caused an economic slowdown and the war in Ukraine, which produces a lot of the worlds grain, has continued the slowdown, such that we're teetering on the edge of a recession, meaning less disposable income for people and industries and it's better to play things safe and conservative for now.