Recently had an appraisal for refinance. The appraiser's estimate was <5% increase from the 16 months earlier when we purchased even though we bought during March 2020 at the height of uncertainty and at a substantial discount.

The reason? No comparable homes that were recently sold AND available via MLS (private sales are ignored). The rules for appraisals breakdown when there is no liquidity. At least Zillow still considered private sales. The Zestimate was much more correct than the "expert" appraiser.