Thanks to its multiverse, the Marvel Cinematic Universe has now been able to make past Marvel movies part of this connected universe, including Fox’s X-Men, but the MCU secretly teased the mutants’ presence back in 2010. The MCU’s Phase 4 began the exploration of the multiverse in the TV series Loki, but it wasn’t until Spider-Man: No Way Home that Marvel confirmed that other movies and characters outside the MCU are part of its multiverse, in this case, Sam Raimi’s Spider-Man trilogy and Marc Webb’s The Amazing Spider-Man movies, as well as Charlie Cox’s Matt Murdock/Daredevil from Netflix’s Marvel TV shows.

https://screenrant.com/mcu-iron-man-2-deleted-scene-mutants-tease/