I seem to have found a fix! I used to cheat "sims.remove_buff buff_campingforest_refreshed" to remove the buff, then I added it again using the same cheat but replace "remove" with "add" and then removed it once more using the remove cheat and it hasn't come back! I saw someone else post this on another thread so I thought I'd give it a go and it only went and worked :D I do have to do this manually every time I come back from a vacation but that isn't too often and honestly I don't mind as it's worth it. Also for the sim who had the loves outdoors trait and had a slightly different buff/moodlet called 'rejuvenated' use the cheat "sims.remove_buff buff_campingforest_lovesoutdoors_rejuvenated", then add it again and remove again as same with the other buff. This also worked. I'll let you know if it comes back without having gone on vacation but so far so good.
P.s. note the space between the two "buff" words in the cheats (for anyone interested in trying this) - also testingcheats must be enabled first which is just "testingcheats on" and lastly the cheat bar is activated by simultaneously pressing Ctrl, C, and Shift keys.
Thanks!