what is considered a good ratting in bitz and bullet chess ?

In online ratings? I'd say:
2000+ is "good".
2500+ is "strong".
3000+ is "incredible".
(Just my perspective on it.)

It's all relative. There are ELO ratings, but the website also tracks your percentile among active players.
The average blitz rating is only 913.
2200 is within a sliver of the top percentile, only one in three hundred players.
Perhaps one in a million players reach the professional level where chess can be one's entire occupation.
1400 is an above average local club player, a rating at which you may never again lose to someone who hasn't taken some time to study chess.
For a coffee break player who is better than their handful of coworkers, perhaps even 1200 will be perceived as good.