Reading barcodes in web frontend JavaScript has long been possible using a variety of libraries such as QuaggaJS.
Now that Google has achieved almost-complete market dominace with their browser engine, the encourage developers to instead use a proprietary #Chromium API that requires end-users to have Google's proprietary "Play Services" installed.
https://blog.chromium.org/2020/04/chrome-83-beta-cross-site-scripting.html
(ctrl+f "barcode")
in case you're wondering, there is a stale bug in mozilla's bugtracker for this https://bugzilla.mozilla.org/show_bug.cgi?id=1553738
The topic of "Google and QR codes" sets me off as I was struggling with customers who distributed their TOTP secret keys (!!!) using google.com/chart
Of course, they followed advices in this thread:
@kravietz yeah, qr code generation libraries / applications using 3rd party servers are a special kind of crapware.