Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

Short answer: GeyserMC sidesteps that player authentication process Java players need to do

Long answer:

I've used and set up GeyserMC before. It sounds like the server you're joining has online-mode on, which requires all Java players who are joining to have a valid Java account and current authentication.

GeyserMC, being a mod to the server, entirely sidesteps this entire process. Your Bedrock cracked client requests to join and GeyserMC, being the way your client communicates with the server, just let's you in. It just sends your client the chunks, the entities, etc. and lets you interact with them, and Java players are shown an additional Player entity (being you).

GeyserMC actually has authentication a server owner can set up that does require a valid Bedrock account or valid Java account, but it seems the server(s) you're playing hasn't set this up.

Microsoft controls the java licenses (you can only buy it from them). This allows them to check that account x has a valid license as they are also linked to the game account

The bedrock licences are tied to other platforms (Google play, apple appstore, ...) and are not tied to the game account. I can login with any account on bedrock (not like java)

I can't speak to the specifics of it, but Bedrock and Java editions are functionally entirely different games. They're designed to function nearly the same, but under the hood, the only real similarities are in the graphical assets. Past the user interaction, they're not really comparable at all.