This is why I get all of these kinds of apps from F-Droid instead of the Play Store. Here's the QR code scanner I use: https://f-droid.org/en/packages/de.t_dankworth.secscanqr/
That's to say:
(a) The time for a given barcode to be accurately detected varies considerably from app to app.
(b) And various apps have different detection capabilities with respect to one another (i.e.: the detection performance varies from app to app depending on the contrast across the barcode image, camera focus or lack thereof, etc.).
(c) For a given app, the detection capability for different types of barcode scans can vary considerably.
For that reason, I have five different QR scanners installed including SecScanQR that you've mentioned and the one with the same namesake as mentioned in this Malwarebytes article.
It seems there's a great deal of variability in the detection algorithms between apps. Unfortunately, from my experience I've found that some of the commercial apps have better detection performance than those on F-Droid—but granted that's only from my limited testing. Which app I use sometimes depends on other features, for instance, the fact that it has a better database or export ability, etc. is more important than the fact that it's insensitive in the detection department.
I wish someone with more knowledge and experience could give others and me the good oil on this. Reckon it'd save us considerable time experimenting.
I'm very happy with it