In the settings of the web vault I can set the KDF Iterations.
The default value is 5000 but below the field there is the text:
Higher KDF iterations can help protect your master password from being brute forced by an attacker. We recommend a value of 100,000 or more.
Warning : Setting your KDF iterations too high could result in poor performance when logging into (and unlocking) Bitwarden on devices with slower CPUs. We recommend that you increase the value in increments of 50,000 and then test all of your devices.
You recommend recommend a value of 100,000 (or more).
So the default value should be increased.