According to VCV Rack support, a change between 2.1.0 and 2.1.1 caused this to happen, but they’re asking the plugin vendors in question to change their plugins to avoid this.
Before 2.1.1 the init() method of the plugin was called first and after that the plugin’s manifest was loaded.
That is reversed in 2.1.1 so now the plugin’s manifest is loaded first and then its init() method is called afterwards, which seems like the logically right thing to do.
That behaviour change bit the Squinky plugin (and others) that was using this behaviour for… something, probably some version-dependent feature detection logic, in the absence of the plugin version being available at init, because the manifest was only loaded later, which has now been corrected.