I have received the solution in another forum:
https://zcusa.951200.xyz/en-us/answers/questions/2124600/sharepoint-and-ms-access-2019
Hi,
Yes, that's a problem with linked Sharepoint lists. The good news is that when you automate the queries with macros or VBA code you can avoid the confirmation messages. In VBA you can use the DAO execute method e.g.
CurrentDb.Execute "YourActionQuery", dbFailOnError
which doesn't raise the (Access) confirmation messages.
The other method is to explicitely suppress the warnings:
DoCmd.SetWarnings False DoCmd.OpenQuery "YourActionQuery" DoCmd.SetWarnings True
This is also available as a macro action (in fact VBA calls the macro action here).
Servus Karl