Did the employees say they have the data to prove it?
No!
Did mgmt. say it?
Yes!
So let's ask mgmt. first to disclose said data.
Got it?
After an initial few-month adjustment period after the shelter-in-place orders my all-remote team at $DAYJOB performed no worse than they had pre-pandemic [0] through to the period where mandatory RTO started being an active fad. During that multi-year "few or no alternatives" WFH period, we all met or exceeded our goals and milestones. We each received raises and/or promotions each year, demonstrating that the business agreed that we were each individually meeting or exceeding our personal performance goals.
Due to my corporate confidentiality agreements I can't provide you with the documentation to back these claims, but they are a true account of the events.
[0] And often notably better, due in part to our ability to fairly-easily flex our schedule to meet with anyone around the world.