'Our sunny days' is kind of slow burn in my opinion. It has romance in less then 20 chaps though
https://www.mangago.me/read-manga/nekama_punch/
this is a slow burn but also one sided love at the start
https://www.mangago.me/read-manga/eternal_covenant/
this is rlly a slow burn and the plot is also rlly good plus fantasy
https://www.mangago.me/read-manga/payback_1/
this is kinda a slow burn but not rlly but they dont ending up doing it until chapter 80
https://www.mangago.me/read-manga/monster_in_the_mist/
deffo slow burn but the plot is alot of action more then romance also enemies to lovers
https://www.mangago.me/read-manga/starting_with_a_lie/
really cute and fluffy and friends to lovers
Hope this helps (=・ω・=)
who can define popularity
lost in the cloud
Rainbow city
When the killer falls in love
My Guildmate Next Door
Reco some slow burn bl