Posting this here from this thread: https://www.reddit.com/r/runescape/comments/vgl0h7/psa_demon_invasion_event_feedback_hotfix/

With the first Demon Invasion wave defeated, we've seen some feedback around aspects of the event that could be improved. Thank you for a lot of the constructive responses we've seen here today.

The team are on top of your feedback and working on putting out a hotfix to address the main concerns.

Our hope is to release this hotfix today and we'll let you know what's changed as soon as it's live.

We have now released a Hotfix to address the feedback around the Demon Invasion Event with a further update to come tomorrow.

Released Today
Updates to the Demon Invasion Event:

-Demons now spawn more quickly

-Demon HP has been increased and scaled to player numbers

-More players are awarded credit for kills

-Cannons are no longer permitted at invasion sites

Releasing Tomorrow
- Demon Invasions will occur every hour (currently every two hours)