Very interesting observation. It could help explain why there's that difference in load times with them. Could show how much better the PS5s decompressor is for kraken then the Series one.
In short, Kraken is the future lossless compression for gaming. Mark Cerny was asked by the devs to adopt Kraken:
|Developers also told Cerny they want support for the Oodle Kraken compression algorithm created by RAD Game Tools. The PS4 used Zlib as its compression format, which the PS5 is also using, but the new console will also support Kraken which Cerny called “Zlib’s smarter cousin”.|
Sony’s chief system architect Mark Cerny has given a “deep dive” of the PS5 console hardware for developers.
The whole industry is moving away from ZLIB to Kraken, according to Mark Cerny.