Just seen this article
It says chrome will close "unused" tabs in order to save memory. The tab will still be visible but its only a placeholder - the site behind the tab will get closed and re-opened when you click on a tab
I already battle with browsers/OSes that want to put things to sleep so I feel this might cause issues for long running Snap! browser tabs - we'll have to see but something to watch out for
FYI - If I want a Snap! project to run 24/7 - I run them in their own browser instance (e.g just 1 tab) on a Linux machine
E.g, I have a project that uses MQTT to monitor cheerlights and also forwards it onwards to a NodeRED flow that makes my Alexa speak out everytime it changes
To avoid any issues while developing projects - make sure you save often!