I got my approval letter back in May and it took about 15 months in total. It arrived a day after civil servants went back to the office after the first COVID-19 wave, so that could well have had something to do with it.
I submitted my renunciation paperwork and sent off the forms to UKVI, but apart from a confirmation number I can't find any way to track its progress or even see if they received my paperwork. The have a call centre that charges by the minute but they can't give personal advice. Has anyone else had to deal with them?