Google Search Console Performance results seem to be day-shifted

Hi

I think the Google Search Console Performance report is not accurate, it seems to be day-shifted. Maybe on purpose, to make technical SEO and observation of their algos more difficult.

Example:
I have a commercial website with about 20 pages, but in a subdirectory I also host a small forum. The forum has a different theme. Due to some mobile theme problems, I changed the forum theme on 21/9/19. On 22/9/19 GSC started reporting Q&A erros on the forum pages (which is accurate).

This changed SEEMS to have negatively affected the rankings, but if you observe the the dates, it seems that Google started to down-rank the page since 10 days earlier, which does not make much sense.

I updated and fixed the forum theme on 11/11/19. On 12/11/19 GSC started reducing the number of error pages, which again is accurate. Again this SEEMS to have benefited the rankings of the page. However that rankings seemed to rise from 3 days earlier on 8/11/19). Again this does not make much sense.

The average rank of the home page for a particular keyword was averaging #10 in August 2019. Then it starts sliding and makes a local deep at #18.4 on 19/9/19 (just two days before I made a change in the theme).

After that we have #18.7 (lowest) on 4/11/19, rose to #12 on 8/11/19, another low #16.1 on 15/11/19, then started rising to #10.6 on 18/11/19 and we have a 3 month high on the last day #9.3 on 26/11/19.