Do you use the "Export package (preview)" functionality in PowerApps to export canvas app?
Do you add a flow connection within your app?
Based on the issue that you mentioned, I have made a test on my side, and don't have the issue that you mentioned.
Please also check if the flow includes a flow connection, if true, please make sure you have enough permission to the flow connection. In addition, if the app includes a flow connection, please make sure the flow has not been deleted, or you could consider remove the flow connection from your app, then try it again.
Also please consider take a try to clear cache of your browser, then try it again, check if the issue is solved.
If the issue still exitss, please consider submit an assisted support ticket through the following link: