They don't.
amio
Newspeak was an intentional in-universe conlang designed and handed down by Ingsoc based on "how you speak affects how you think" (which is a hypothesis that has... some kind of name). This is a bunch of people trivially avoiding automated filtering like it's been done since the first puritan implemented the first world filter.
One of the main differences is that self-censoring seggs and raep and ahh-es or whatever still leaves it plenty obvious what you mean, it just outs you as a Tiktok user. Conceptually word filters are a blacklist whereas Newspeak was intended to be a whitelist with the restrictiveness that entails.
"We will be GLAD to return when Christians & Those who fear God and HATE evil! Thank ------ You,"
... yeah, that seems about right.
Vagal tone, is the technical answer. A nerve (vagus) runs through your body and, among other things, slows the heart. When straining to "void", you cause that nerve to activate more strongly. It's also related to the Valsalva maneuver.
Not ridiculously pedantically, of course... but yes