Hi @jensa. Just one correction to what you wrote: this is not an error. It is only some informational output.
For some reason, the developers of the AVRDUDE uploader tool decided this information was useful enough to the user that it should be printed even when the verbose output is not enabled. It is not clear to me whether the information could be useful to those who use AVRDUDE directly from the command line, but it surely isn't anything of interest to the average Arduino IDE user. But this is a 3rd party tool, so we take it as it comes as long as there isn't a serious defect.
Arduino IDE 1.x suppresses all output from the upload tool when the user's "Show verbose output during > ☐ upload" preference is disabled. This took the control over the communication with the user away from the tool and boards platform author. So in Arduino IDE 2.x the IDE was changed to always print any output from the tool. Each boards platform author can adjust the upload command pattern according to the user's verbosity preference.