Peggy Carter has evolved drastically in the Marvel Cinematic Universe to such an extent that she seems like a Captain America replacement, thanks to her appearance in Marvel’s What If…? season 2. Introduced in Captain America: First Avenger as a British intelligence officer and founder of the anti-Hydra collective Strategic Scientific Reserve, Carter initially appeared as Steve Rogers’ superior and later became his short-lived love interest. Apart from her arc being fleshed out further in the live-action series Agent Carter, an alternate version of the character also wielded Captain America’s shield under the alias Captain Carter in What If’s debut season and Doctor Strange in the Multiverse of Madness.
https://screenrant.com/captain-carter-controversy-mcu-explained/