Dahlia 'Fascination'

Edited: this has been identified as a dahlia. Thanks to all who helped! It sprouted up randomly in one of our lanai planters and I haven't been able to identify it. The plant is tall and spindly with reddish-dark green leaves. So far it's only put out one flower at a time, approximately 1.5 to 2 inches across with a dark pink bloom that becomes bright pink before dying off. Any thoughts?

I think it's a Dahlia, but not sure what type. Maybe Bishop of Llandaff? They're usually red but sometimes come out pink too.

@savannahssucculentgarden I think you're right! I did some googling and I believe it's a Fascination dahlia but I'm going to keep digging a little before I update the identification. Thank you for pointing me in the right direction!