Unfortunately limiting the duration won’t make a blind bit of difference as one of the symptoms of the screwed up update notifications is the duration function doesn’t work either. Along with the Tip/Ads popup instead of update notification popup and no voice over.

The only way to deal with it as has been mentioned in many topics is:
These tips popups have in the past been piggybacked with the auto update update notification, so the only way to get rid of them would be to disable the auto update notification, which if you want the update notification (when it works correctly) would remove everything.

avastUI > Settings > Update - scroll down to Details and uncheck the ‘Show notification box after automatic update.’

@ Coffee addict
I think this is a happy coincidence as I have had these options unchecked for some considerable time in avast and it doesn’t stop the screwed up auto update bug.