Podcasts disappeared from iTunes

I had over 2,000 downloaded podcasts that were in iTunes, song of the day stuff, and as I would listen to them, I would edit the info and change them from Podcast to Music and save them in my iTunes library. Life got in the way and didn't think much of it. Just got a new Mac Studio and see that Podcasts and iTunes are separate much like my phone or iPad. When I opened up Podcasts, I watched as the number of podcasts kept going down until they were gone. What happened? If I still have them on my iPod, when I sync my iPod to iTunes, will they show back up in my Podcast or ITunes library? Or are they on my Time Machine backup so I can restore them?