My understanding is that EU regulators had an issue because Windows Defender rolled out kernel mode/kernel data protection, which gave Microsoft a de-facto monopoly in that market segment if no one else was allowed to use the same technology in their products.
Microsoft complaining that the Crowdstrike incident was the EU’s fault is an argument in favor of a Microsoft monopoly, which the EU has been pretty consistently against, and EU opposition to this should not have been a surprise to Microsoft.