In Hong Kong, Lexias pardalis (a species of butterfly) was quite a rare species and can be found only in select areas within the country. When it became a lifer for me back in April 2018, it was still rare and restricted, but fast forward several months, I see observations of that sp. blowing up on iNat, and now it is not an uncommon sight, and can be found all around the country now. So this is a recent change, and I’m not sure about historical records.
2015 - 3 observations (year of 1st record in iNat in Hong Kong)
2016 - 2
2017 - 9
2018 - 45
2019 - 377
2020 - 376
And becuase the majority of inatters are just casual ones I dont think the lack of observations in the previous years was due to people just not spotting it.