With Release Wave 2 2022, the old advanced find will be removed and the new advanced find experience will be its replacement. However, there are many old goats, like me out there that still want to use the old advanced find. I think one of the main advantages of the old advanced find is that it is not bound to the tables/entities of the specific app which makes it easy to have a look at things that are a bit more hidden from normal view. The new experience will require you to, in essence, create an admin app with all the required tables. Another option is of course to use Jonas Rapp’s Fetch XML Builder to find what ever you need, but that has another level of geek to it that might not fit all superusers out there. (Although I think they really would like it if they learnt how).
So, with the following URL you can still access the old advanced find and you can hence just bookmark it and have it easily available. How long this will be the case, I cannot say. But probably a year or so. And do send your feedback to Microsoft of the new experience so that they can make it as good as it should be.
For example, with instance contoso in region 1 (USA):
Note that you do not actually have to include the app as a query parameter.