The grey zone tactics, by definition, are actually a combination of all kinds of military or non-military threats that they can impose, in this case on Taiwan. It's a grey zone, so it's very difficult to see or regard them as war behaviour. This constrains the other foreign countries from reacting. If it's war behaviour, then perhaps international condemnation and sanctions would come immediately. China is trying to avoid that.
Again, Taiwan's situation is so unique. It's different from any other country's in terms of what you perceive as Chinese grey zone tactics. In Taiwan the grey zone tactics are a combination of their disinformation campaign, cyber-attacks and cognitive warfare. They create all kinds of scenarios to confuse society and confuse voters in order to nurture a candidate of their liking.
It's things like that. It's not what NSICOP has found out in Canada. It's one or two notches higher in Taiwan.