Does Mortgage exemption stop you switching?

[irishfinanceguy]

if you get a mortgage exemption by a provider say 4.5 exemption, does that in effect stop you from switching until you get to the more usual 4x mortgage salary?

Looking for first time mortgage here and want to maximise what I can borrow but also maximise cash backs if possible

Seems like both cant be done as not all providers will give me the 4.5 x salary exemption

Thanks