I got some good sign-up bonuses at the beginning of 2020 by putting travel on some new cards. I utilized the bonuses. Then I got reimbursed for travel due to the pandemic, so had negative balances. And just got done closing the cards to avoid the annual fee (waived the first year). They didn't try to claw-back the rewards.
I'm reporting no dollar figures, because my choice of accounting methodology doesn't make it easy; I don't keep a separate asset account for each card's points. And the kickbacks get allocated to the original spend category. So, for example, if that month's card was used primarily for travel, then the kickback would just be used to reduce the travel total for the month. Those kickbacks don't look much different than, say, a payment, so hard to write a report that pulls them out for reporting. I might be able to do it, but lack motivation.
I've asked this question before, a long time ago, if people keep an asset account for points. Seems like a lot of work. With our 2% Fidelity cards, when the kickback arrives, I just ping-pong it back as a payment against the card using Fidelity bill-pay back to Elan.
One last comment...on the 6% groceries Amex, I did an analysis (kind of a PITA), and determined it was no better than 2% on the Fidelity card for us because of the $95 annual fee and the fact that our groceries often come from places not considered "grocery stores" in the eyes of Amex. So dumped that card, along with it's annual fee.