Have you set up a Common Data Service data source within your DEV Environment?
Have you assigned appropriate role of this DEV Environment to your end users?
Does your canvas app using CDS Entity as data source?
I have made a test on my side, and don't have the issue that you mentioned. Please check if you have set up a Common Data Service data source within your DEV Environment already. If not, please create a Common Data Service database within your DEV Environment.
In additon, also please check if you have assigned proper security role of your DEV Environment to your end users. You should assign Environment Marker role of your DEV Environment to your end users at least.
Also please check if your end users have proper License to access PowerApps, and the license is not expired.
Community Support Team _ Kris Dai If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
We did not setup a CDS database for this environment because we don't run any model-driven apps. Unfortunately, "something" triggered the security for this environment to be "pulled into" Dynamics. When this happened, all users of the environment lost permissions or started having errors like the one above. Not good.
There are no logs to review to determine why/how this event occurred nor how to prevent it in the future.