Code error: platform.txt from core 'DFRobot Boards' contains deprecated recipe.ar.pattern

I’ve been trying to program a DFRobot Bluno board with Arduino software recently. It worked fine before but now I keep getting the following error:

Arduino: 1.8.13 (Windows 10), Board: "Bluno M0 MainBoard"

Warning: platform.txt from core ‘DFRobot Boards’ contains deprecated recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} "{build.path}/{archive_file}" "{object_file}", automatically converted to recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} "{archive_file_path}" "{object_file}". Consider upgrading this core.

Sketch uses 11956 bytes (19%) of program storage space. Maximum is 60416 bytes.

I get the same error no matter what code I am running and no matter what computer I am running it on. The libraries, cores, and software is all up to date.

This is the board manager url I used: https://raw.githubusercontent.com/DFRobot/DFRobotDuinoBoard/master/package_dfrobot_index.json

Could it be something DFRobot has changed in their libraries? Do I have a faulty board?

Thanks.