Can someone suggest a better title? Better here means "accurate and neutral, and preferably using representative language from the article".
The language changes here are slight (claims -> warns) and includes more context about the reason this watchdog is speaking out (current debates around the Counter-Terrorism and Border Security Act, new implementation of the National Security Act), using language from the first 4 paragraphs (may be considered, could be considered, stark warning, report warns, etc).
You could also leave out the specific names of the acts—they're not super helpful to me as a non-UK news consumer, but I suspect they might be more crucial to someone who's tapped into the UK political news cycle:
"Creating apps like Signal could be considered 'hostile activities' under new laws, UK watchdog warns"