They changed the English requirement for those getting the extension visas or FLR. Technically, your English proficiency should be increasing as the time goes on living here in the UK, hence they want you to have passed an A2 level English test. You can find more details here.

https://www.gov.uk/government/upload..._of_intent.pdf

If the test you submitted for your spouse visa is just A1, you need to take a new English test to pass the A2 level. If I were you though, I would rather get a B1 level in English because it will save you getting another English test for ILR and citizenship.