Automods for certain Subs banning for no reason

Im wondering on what basis these automods in certain subs banning users when they post thinking we are spammers/ bots . Clearly I got nothing on my profile I just here and there and make some comments keeping myself active here but how do these mods think Im a bot or spammer.

Also is there any where to check (besides rules listed by the mods in each subs ) that whats the reddit age and karma count required in order to post or comment ? I have seen few subs dont mention anything about the age or karma count in the rules but I cant post or comment on those subs.

TIA