I was able to fix the issue but still don't quite understand the why. We have Codeigniter 3 and Codeigniter 4 running side by side while we do a large migration project. I had my index.php for CI3 set to the production database. When my .env for CI4 was set to development, things didn't work. When I changed the index.php to development, and the two matched, I was able to stay logged in.

The code for CI4 pages shouldn't be hitting CI3 code, so I'm going to try to track down why that was happening. It's a complex configuration we have going on, but we have an extremely large code base that needs to be rewritten.