A while ago, Apple caught a bit of heat for admitting they throttle performance of older iPhones. Prior to the company's official statement on the matter, rumors began to spread that the company performed "planned obsolescence" by pushing older iPhone owners to upgrade to the latest devices.
This was something the company unequivocally denied in their initial disclosure, stating they only degraded performance to improve device lifespan and prevent random shutdowns due to aging batteries.
The company started by offering $29 battery replacements to owners of the iPhone 6 or newer until the end of 2018 - a $50 price cut compared to the normal $79 fee. Later, Tim Cook announced iOS 11.3 would include the option to turn off performance throttling entirely.
Recently, Senator John Thune sent a letter to Apple asking, among other things, whether or not the company would be offering rebates to customers who purchased a battery replacement prior to the $50 discount going into effect. In response, Apple has now stated they're "exploring" the possibility and will update Thune accordingly.
Senator Thune thanked Apple for their reply in a statement. "I appreciate Apple's response to my inquiry and the company's ongoing discussions with the committee. In those conversations, Apple has acknowledged that its initial disclosures came up short."