So i saw it either earlier this year or last year and it only had a couple chapters. The plot was the main character was a saintess who was maintaining a barrier around the country to keep out monsters. I think she was supposed to have been from another country in that world and was engaged to one of the princes. The prince found who he thinks is the actual saintess and that the mc had been taking credit for her power so banishes her. Believing the other girl to actually be one she lowers her barrier as they also block the growth of other saintess powers. She leaves with her female knight friend and i think go to an adventurer's guild to get an escort.

that's all i recall. I don't think there was any isekai aspect to it.

when baka's search is too baka you can still use google (and probably some other search engines) https://www.google.com/search?q=mangaupdates.com+barrier+saint

this, maybe? https://www.mangaupdates.com/series/12573la/shin-no-seijo-de-aru-watashi-wa-tsuihou-saremashita-dakara-kono-kuni-wa-mou-owari-desu

or this? https://www.mangaupdates.com/series/ktmjcqv/kanpeki-sugite-kawaigeganai-to-konyaku-hakisareta-seijo-wa-ringoku-ni-urareru