It does take 5 years… because needs to apply for and be granted ILR before she can qualify for UK citizenship, and it takes 5 years of living in the UK on spousal visas in order to qualify for ILR.
When you renewed her visa, she would have applied for and been granted FLR(M) (Further Leave to Remain), not ILR.
So, if she arrived in the UK on her spousal visa in 2019, she will qualify for ILR in 2024.
Once she has been granted ILR, she will be able to apply for UK citizenship, showing the most recent 3 years of residency in the UK
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