Windows, Chrome 93.0.4577.82
When you choose date diapason with only start date chosen, then go further, e.g. click on “your observations” button, then need to go back again, in this moment you can see how URL is changing, adding the same date for the end of diaposon.
I start with https://www.inaturalist.org/observations?d1=2021-09-06&place_id=any&user_id=melodi_96&verifiable=any
Click on my observations and go to https://www.inaturalist.org/observations?place_id=any&user_id=melodi_96&verifiable=any
Then click back in browser and somehow get to https://www.inaturalist.org/observations?d1=2021-09-06&d2=2021-09-06&place_id=any&user_id=melodi_96&verifiable=any
this seems like it’s some variant of the problem previously reported as: https://forum.inaturalist.org/t/verifiable-false-in-url-strange-behaviour/9682
the keys to reproducing are that (1) you need to keep the Filters menu open (don’t click Update) when (2) you click on Your Observations. (here, you’re not clicking the Your Observations check box in the Filters menu. you’re clicking the Your Observations link the the main menu, which will take you to an Explore page that’s preset with just your observations.)
Yes, sorry that I didn’t specify it, I didn’t think about button in filters, interesting that it doesn’t work that way if I choose the end date, only first one.