Hi Samarth,
Thank you for bringing your question about the new requirements when updating to the new SDK. If your old SDK was below 7.42.0 then when updating to 7.42.0 or later it will be necessary to add for Ad Manager a key GADIsAdManagerApp with boolean "yes" to the Info.plist as described here, and that addition should remedy your crash and initialize the SDK correctly. For AdMob the SDK needs a different addition to Info.plist - GADApplicationIdentifier with string of app Id as described here.
Regards,
Aryeh Baker
Mobile Ads SDK Team