Slip on exhaust, good or bad for the engine.

OK Guys, once and for all, does a slip on exhaust silencer fitted to a 2020 Z650 damage the engine? Lean fuelling etc. I thought that the onboard computer and the O2 censor would automatically make its own fuelling adjustments based upon the less air restriction of a slip on.
Your comments please, facts and truth would be useful.
Thanks and Ride Safe.