I think it's inevitable that as we grow some people will get left behind. Sometimes the people that have known us the longest get hung up on seeing the old version of us and when we make efforts to progress in life they sabotage us by planting seeds of guilt and doubt in our minds. The fear of being left behind will make people stoop low to do such things but just because someone is comfortable with staying the same, that doesn't mean you let that stop you from progressing.
I believe, in life, we have different chapters that represent a stage of growth and each stage requires different people to support us and offer wisdom, for us to feel fulfilled. To me, friendships should be nourishing and inspiring.
It's bittersweet but don't let loyalty be the reason you hold onto dead end friendships, you owe it to yourself to be the best version of you and if your friends are holding you back from that then you need to proceed in life without them. Anything that hinders your growth is unhealthy. Outgrowing people is a sign of growth, you're no longer the person you used to be and that's a good thing (providing that you changed for the best and not the worst lol). Try not to feel guilty but instead embrace it and see it as a part of life -the only constant in life is change. Be brave enough to move forward and find your tribe so you can thrive in life.