Hi @summitb,
I have made a test on my side and don't have the issue that you mentioned.
I agree with @timl's thought almost. If you want to use Salesforce connector within your app, you need to subscribe PowerApps Plan 1, Plan 2 or Dynamics 365 Plan.
More details about the requirments to use the PREMIUM connectors within PowerApps, please check the following article:
https://powerapps.microsoft.com/en-us/pricing/
Please check if you have subscribed proper PowerApps Plan on your side to use Salesforce connector within your app.
If you have subscribed proper PowerApps Plan to use Salesforce connector within your app, but the issue still exists, please take a try to check if you have provided proper credential to sign in Salesforce service within your app.
Also please take a try to clear cache of your browser, then try it again to check if the issue is solved.
Best regards,
Kris