Is continuing to supplicate for the return of a blessing that was taken away due to sins, after repenting and regretting them, considered a form of dissatisfaction with Allah’s decree, or is stopping the supplication considered despairing of Allah’s mercy and power?

Sins remove blessings and bring misfortunes. Your persistence in supplication is a great act of worship and one of the strongest means to achieve what is desired, for destiny is determined by means, and supplication is one of them. Giving up hope, abandoning supplication, and believing it to be useless is a form of despair and despondency concerning the mercy of Allah Almighty, and it is a major sin. We advise you to be optimistic and continue to supplicate, seeking out times when prayers are answered, staying away from sins, and being wary of despair.