Xiaomi may have recently upgraded the global and Indian versions of the Redmi K20 and Mi 9T to MIUI 12, but it has not granted the same update for the EU editions. Instead, the company has pushed a new MIUI 11 update that merely includes the May 2020 security patch. Called V11.0.6.0.QFJEUXM, the update is rolling out now to select handsets as an over-the-air (OTA) download ahead of a wider release.
Additionally, MIUI 12 for the EU version of the Redmi K20 Pro and Mi 9T Pro has also been delayed. According to a moderator on Mi Community, the OS upgrade has been held back because of bugs. We would expect Xiaomi to finish Round 1 of its MIUI 12 release schedule before it starts Round 2, beta testers for which it is already recruiting.
Alternatively, you could flash the global versions of MIUI 12 to your EU Redmi K20, Redmi K20 Pro, Mi 9T or Mi 9T Pro. You must unlock your device before you can do so, but Xiaomi provides a guide on unlocking your device.