Tiny chat JPEGs do not have the frequencies a sharpener wants. One hard enhance then invents crunchy edges. A milder sequence is: upscale a little, then a light local deblur on the subject only, then stop. I keep that sequence in the browser at https://mejorarcalidad.com/ when the job is simply mejorar calidad de imagen before I send the file again. It will not rescue a missed-focu... https://mejorarcalidad.com/