I had an FTP at the end of 2019 of 246W (TR ramp test). Then I had a cold and didn't train for a couple of weeks. Tested mid January at 225W, then had another - bad - cold and by the time I was training again, FTP was 215. Trained for a bit then lockdown started, which disrupted things initially, and then I had June off training as I dealt with real life stuff that lockdown had prevented. My FTP had increased to 243W by September when I developed a heart rhythm* problem which ended up with loads of tests and advice to avoid max intensity effort for a while. ECGs, heart monitor for two weeks, cardiac echo, and CT angiogram eventually decided I was probably ok. The heart rhythm problem went away on its own last month. While I was avoiding max intensity I followed a more Z2 focussed plan with more volume and less intensity.
Upshot is I did the ramp test in December and FTP was 251. This is the best score I've ever had on the TrainerRoad ramp test. I did pretty much the same number of outdoor rides in 2020 as 2019 (around 30 in both cases). But the longest ride in 2020 was 129km; the longest in 2019 was 1230km.
For this lockdown I'm not doing the long z2 focus as it's not compatible with sanity indoors. I'm doing something in-between the mid-volume and high volume Sweet Spot Base plans from TrainerRoad. I'm trying to do a couple of long z2s a week, aiming for Wednesdays and Sundays. Goal is 3h. As long as I can actually leave the village this can be done locally with a loop of 10 or so miles. The village is too small, and its streets too narrow, for any sort of training ride to take place within its boundary. I'm unlikely to be exposed to Covid in day-to-day life and haven't had any sort of cold since those two colds in January, so I'm aiming for steady progress.
Edit: also did some rowing during the summer, and gained some confidence in a single. Stopped when the heart problem started and have been scuppered by usually being in a different tier than the rowing club, there being too much water in the river, etc.
* Premature ventricular contractions - usually benign but can be a sign of a serious issue. I was having them basically all the time, roughly 1 beat in 8 over a two week monitoring period, which is very frequent.