Platform: Website
Browser: happens in Firefox 83.0 (Mac) as well as in Safari
URLs (aka web addresses) of any relevant observations or pages:
open in separate tabs:
https://www.inaturalist.org/observations/66215168
https://www.inaturalist.org/taxa/76067-Carex-leporina
Screenshots of what you are seeing and Description of problem:
Open two browser tabs: one of an observation, another one of a taxon page where that taxon is part of the ID process in the first tab (here Carex leporina is a withdrawn ID)
Change the language of the observation page (here from German to English)
Result: Language is changed, but URL switches from observation to taxon page of the other tab
This works also the other way round:
Taxon page: https://www.inaturalist.org/taxa/76581-Cynosurus-cristatus
Observation of that taxon (although withdrawn): https://www.inaturalist.org/observations/25831529
Changing language of the taxon page (Cynosurus cristatus) will reload the observation of the other tab
Attaching ?locale=en in these cases is working fine.