Is the scratched out Hint in the photo your hint? If that is your Hint, then it appears you did not properly erase the Mac. The good news is it appears Filevault is enabled so as long as the new owner is not able to guess the password from the Hint, then your data should be safe (it is only as safe as the password used though).
FYI, here are all the steps you should have performed prior to selling a Mac:
What to do before you sell, give away, trade in, or recycle your Mac - Apple Support
You neglected to mention the exact model of this Mac. This is very important because the procedure to erase an encrypted Mac is different between the older models and the newer 2018+ Macs (T2 & M-series models). If it is an older 2017 & earlier model without the T2 security chip, then you can just have the new owner erase the whole physical drive using Disk Utility (see the "Erase" instructions in the Apple article I linked.....Step #5). This will allow the new owner to erase & properly reinstall macOS. Since you had Filevault enabled, it will destroy the ability to access.
If it is a 2018+ Mac with T2 chip or M-series Mac, then it will likely require access to another Mac running macOS 26.x Tahoe (possibly macOS 15.x Sequoia) to perform a DFU Firmware Restore....I'm not entirely sure if that will work....it should if FindMy is not enabled. One of these models may require you to get the laptop back & properly erase the system using the Apple article I linked.
