Hi @spendler ,Welcome to the forums!
It looks like the Blueprint lost references to variables that previously existed and are no longer valid. Basically, this means that the Blueprint you were casting to either no longer exists properly, was renamed, or the reference simply got broken. It also looks like there are variables that no longer exist inside that Blueprint. This usually happens when you delete referenced content, rename assets, move files between folders, change the project version, or copy nodes from another project.
To fix it, you would need to delete the broken Cast node (Bad Cast Node) and create it again. From Get Anim Instance, search for the correct BP_Animation again and reconnect everything. And regarding the variables, you would need to recreate them inside the corresponding Blueprint (the one referenced by the Bad Cast Node), since the error indicates that they currently do not exist, which is why they appear grayed out.
Hope it helps!