The two processes are effectively unrelated.
Finanças - you are required to update this as soon as reasonably possible when your address changes; but the impact of it on your change of residency documentation in your case is almost certainly nil.
Post-Brexit replacement documentation - as you probably know, this is done via brexit.sef.pt not in person. At present, this consists of registering for the transfer (you need to register on the SEF main site first, then go to brexit.sef.pt to apply to exchange your document. When successfully done, it will generate a code you can print and will need to use when travelling, to return to Portugal as a resident (otherwise it doesn't really do much).
Whilst the intention had been for people to be contacted for an appointment to take fingerprints and do other formalities, to issue the cards, this is delayed due to COVID, with no clear indication as to when it will start.
Meanwhile, keep your old document, and the printout of the code from the brexit.sef.pt site, together, to use whenever you need to evidence your residency status.
Discover the beautiful Ribatejo!
Need help with planning, surveys and restoration? Contact us!
reabilitejo.pt or facebook.com/reabilitejo