KV mismatch in GAM: cust_param handling in gamAdServerVideo.js uses formatQS() which handles arrays explicitly with bracket notation

[suchhanda-crazygames]

The cust_param handing in getCustParams() func in modules/gamAdServerVideo.js uses src/util formatQS() which handles arrays explicitly with PHP-style bracket notation. This converts custom KV pairs, which needs to be sent to GAM, like below:

From:
bidders_enabled: ['ix', 'rubicon']
to
bidders_enabled[]=ix&bidders_enabled[]=rubicon

causing reporting mismatch in GAM.

I can see that this func was added in this commit along with func parseQS (which does the opposite and removes the [])

I see only 2 consumers feed formatQS() a raw JS array and trigger k[]=v output:

1. gamAdServerVideo.js where the issue is happening
2. adlooxAnalyticsAdapter.js where i see a comment addressing the issue.
3. modules/adlooxRtdProvider.js - which uses buildUrl(internally uses formatQS) and then strips the []

I can also see that libraries/medianetUtils/utils.js has pivoted to use its own formatQS definition.

[dgirardi]

It's possible that noone wants the brackets but I don't think that's easily confirmed. For now #15358 addresses gamAdServerVideo.

There's also

Prebid.js/modules/targetVideoAdServerVideo.js

Line 68 in 00d43e6

...bid.adserverTargeting,

which may or may not need the same fix; the same encoding is also used in

Prebid.js/src/ajax.ts

Line 72 in 744c378

url = buildUrl(urlInfo);

[patmmccann]

marking high as confirmed bug