Exactly, even Chelsea finished low 2/3 seasons back but now they are World champions, Nottingham as you said are also good example even when they deserve a spot in the champions league. They did really well and even this coming season I expect them to perform even better but this season will be though for everyone. Any team can improve and I won't be shocked if Manchester United also show some improvements.
Nottingham forest were set to qualify for Champions league but they were not able to perform well towards the end of 2024/25 EPL season. Nottingham forest finished 7th last season and they must be happy that they atleast qualify for UEFA conference league. That's a big achievement for a team that finished just one spot over the relegation zone in 2023/24 season.
United finished 15th last season and as I said if Nottingham forest can make a comeback in next season then any team can do that provided they identify their weaknesses and fix them.
I was seriously supporting Nottingham forest last season because they really show a lot of Incredible performance which was to my test and for a bottom team to pick a courage like that by making like difficult for the top teams including Liverpool who are currently the title holder, the really make life difficult for Liverpool because they are the first teams to defeat them at their home. But along the line they declined which I was so disappointed with their performance. So for the coming season I don't think they could have that chance again because many teams have wake up, the like of Chelsea, Manchester United and Manchester City, these three teams have lost the form last season but this season they are all back with full force.