There is a product issue using virtual tables with OData v4 Data Sources that require an authentication header. The allowable size of the column used to store the header value is limited to 1024 characters. This was originally opened in a support ticket and was confirmed during a call with a Power Platform CSA.

We attempted to use an OAuth bearer token for authorization, but it was ~1,200 characters and was truncated when entered manually in the UI form. The documentation on request parameters led us to believe this was supported but the underlying Dataverse table called "OData v4 Data Source" has a max size of 1,024 characters for the "parameter*value" columns. We suggest the size should be increased to something larger to accommodate larger token sizes.