Hi,
with PR Upgrade plexus-compiler-eclipse and ecj, req. Maven >= 3.9.6 by holgerfriedrich · Pull Request #4664 · openhab/openhab-core · GitHub merged today, the minimum version for Maven raises from 3.6.3 to 3.9.6.
This is due to a dependency of plexus-compiler-eclipse, requiring Maven 3.9.6 or later.
Please update your development environment if required.
btw: I have not tried Maven 4.0.0 preview yet, so my recommendation stay with 3.9.x series.