KSP 1.11.0 broke a lot of old add'ons

OPT Legacy

OPT Legacy also broke due this problem.

Not tested it myself, but this was reported here:

Warning. WorldStabilizer no longer suppresses the 1km spawn bug as of KSP 1.11, and seems to actually evolve it into a new and vicious kraken.

Take extreme care when spawning crafts containing the following parts, or just don't use them anymore: