This site uses the Speculation Rules prerendering feature which is available on Chrome Android from 103 and Chrome Desktop from 105.
Otherwise, if you using a different flavor of Chrome, then to enable the prerender2 flag:
timer.html timer.html?target_hint=blank: simple demo
nested.html: prerender from a prerender
subframe-container.html: page with a subframe
countdown.html: page with a countdown timer, for PBA demo.