The hope is that Horizon Forbidden West is confirmed for release later this year, but the source who reported the rumor is definitely trustworthy for the Guerrilla Games stuff, so there's a good chance it won't lie (of course we don't take anything for sure).
If that happens, the only absolute exclusives of PS5 in 2021 would remain Returnal, out in a few weeks, and Ratchet & Clank: Rift Apart, out on June 11 2021. If we want, we can also count in the pile also Destruction AllStars, given away in February with the PlayStation Plus, but honestly we struggle a bit to consider it an exclusive of weight. Considering the exclusive thunderstorms and the double A the situation improves, but there is a reversal, or at least a pairing to Xbox compared to what were the initial prospects. Currently with Halo Infinite, Microsoft Flight Simulator and probably Starfield (of which the exclusive has not yet been confirmed), Xbox Series X seems to be able to finish the year with more exclusives than PS5, with the risk that Bethesda will pull something out of the cylinder that we do not yet know. We'll see with the next events, what will actually be announced.
[Errata corrige]
We had mistakenly entered Psychonauts 2 as an Xbox exclusivity, but it will also be released on PS4. Sorry for the mistake.