The legacy linking feature results in a weird behavior when done repeatedly. It looks the parts lose their physical properties. Even though KAS doesn't mangle with it explicitly. Specific for KSP 1.11 and KAS 1.7. Some of these symptoms can also be observed in W1/W2 parts behavior when the externally attached part is incompatible.

Video: https://youtu.be/OnKk79VKdok