I guess this was the long play Samsung had in mind. Bribe AMD by purchasing their GPU tech and putting it in their smartphones and let them gain traction there in return for foundry orders because they couldn't get anyone to purchase chips otherwise.
The exclusive collaboration with TSMC seems to be coming to an end as AMD is now reportedly collaborating with Samsung for the upcoming Zen 5 Prometheus processors. TSCM would still handle the production of the advanced cores on the cutting-edge 3 nm nodes, whereas Samsung is to produce the "basic" Zen 5c efficiency cores on its 4 nm nodes.