https://www.bleepingcomputer.com/news/security/stop-ransomware-decryptor-released-for-148-variants/

A decryptor for the STOP Ransomware has been released by Emsisoft and Michael Gillespie that allows you to decrypt files encrypted by 148 variants of the infection for free.

While the decryptor can recover files for 148 variants, it needs to be noted that anyone who was infected after August 2019 cannot be helped with this service. With that said, it may be possible to decrypt using an offline key, so even with these variants there may be some success.