Your first mistake is posting a question without  providing adequate information to effectively answer it.  Second mistake is it appears you haven’t familiarized yourself with the IRC.  

To receive capital gains exclusion, property must be occupied in 2 of the last 5 years.  2018 - 2021 is 4 years.  Additionally, depreciation recapture would result in a basis reduction which, in turn, probably increased the capital gain.   I’m attaching a helpful link.  

https://www.marcumllp.com/insights/converting-a-personal-residence-to-rental-property

also beware that there are other issues to consider.  For instance, were there multiple rental properties being run as single or multiple businesses?