From what I've read, Bosa is fine with getting either no offset language in his contract (so his money is 100% guaranteed) -or- he wants 100% of his signing bonus upfront. That's about all that's negotiable with rookie contracts since the restructure, and it's standard that high draft picks tend to get one or the other. As Texas already explained, this is why the Chargers' final offer was, money-wise, more than Goff's (Chargers offered Bosa close to his full 100%, but Goff negotiated for offset language in his contract and is deferring much more of his signing bonus). Basically, Bosa is justifiably angry that the Chargers won't give him either one (100% upfront or no offset language) when it's totally standard procedure for high draft stock players. And the Chargers are just doing it to set a precedent for their future draft picks anyway so they can continue to be stingy assholes nobody likes.
On the other hand, it's totally reasonable to say that Bosa is still getting more than he should and he needs to stop being an entitled bitch about the whole thing. Like, bro, I think you've more than proven your point by now and regardless of standard procedure, you're still getting more than you objectively should. Most people would kill to have your position in life and here you are being a spoiled princess splitting hairs over amounts of money relatively few will ever come close to seeing. He's just harming his own future earning potential, and reputation, more than the Chargers' already poor one, solely on principle.