You have not provided any evidence for that or explained what you mean. Are you using a specific version of Gemini via a service, api, Gemini app? AI studio? etc? I have noticed zero issues.
But in the last month Gemini 3 flash was released, are you getting confused between models? (Although in my experience Gemini 3 flash is excellent)
I haven't experienced any degradation myself, but many times people attribute this to companies running quantified versions of the model during peak demand