https://github.com/quarkusio/quarkus/wiki/Migration-Guide-1.12#mutiny

Deprecated methods and removed methods declared within these 2 interfaces
Multi.java
Uni.java

Use this rule as a basis
So the rules are seraching for io.smallrye.mutiny.InterfaceName.MethodName()
Where InterfaceName is Multi or Uni
And MethodName are those in the Migration Guide.

A separate focused rule is required for each bullet point in the Migration Guide.
1 SP
link to Mutiny section of the guide.
The deprecated methods are all Potential.
The removed methods are Mandatory.
All except multi.transform().first/test/filter -> multi.select() and multi.skip() should have a quick fix

Note for QE
When referring to class names Uni and Multi the message in the rules have deliberately got them starting with a capitai letter.
Which is different from the guide, but correct nevertheless.