A few things come to mind. First, just making sure that they are indeed healthy and well-recovered from the neuter. This means ensuring that they are eating (which it sounds like they are) and that poop/pee is looking normal. When they are moving, also making sure their movements look natural and healthy and not potentially hampered due to the procedure.
Another thing is just the time needed to “normalize” after a neuter. Usually it’s a craze, but perhaps your rabbits reactions are just unique in they want some time to recover to themselves and are impacted differently.
Lastly, I also just think about rabbits getting older (even when they are objectively young), they just get less energetic. My 4yo rabbit rarely binkies anymore, and I’d say that started when he was 1-2yrs old.
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.