On the same computer, on the same browser client.getFonts() Run it twice and the result is different in fireFox #128

browser info: {"name":"Firefox","version":"92"}
Sometimes the getFonts you get are the same, sometimes they are different;
First Time:
fontList-- Agency FB, Aharoni, Andalus, Angsana New, AngsanaUPC, Aparajita, Arabic Transparent, Arabic Typesetting, Arial Baltic, Arial Black, Arial CE, Arial CYR, Arial Greek, Arial TUR, Arial, Batang, BatangChe, Bauhaus 93, Bell MT, Bodoni MT, Bookman Old Style, Broadway, Browallia New, BrowalliaUPC, Calibri Light, Calibri, Californian FB, Cambria Math, Cambria, Candara, Castellar, Centaur, Century Gothic, Colonna MT, Comic Sans MS, Consolas, Constantia, Copperplate Gothic Light, Corbel, Cordia New, CordiaUPC, Courier New Baltic, Courier New CE, Courier New CYR, Courier New Greek, Courier New TUR, Courier New, DFKai-SB, DaunPenh, David, DilleniaUPC, DokChampa, Dotum, DotumChe, Ebrima, Engravers MT, Estrangelo Edessa, EucrosiaUPC, Euphemia, FangSong, Forte, FrankRuehl, Franklin Gothic Heavy, FreesiaUPC, French Script MT, Gabriola, Gautami, Georgia, Gigi, Gisha, Goudy Old Style, Gulim, GulimChe, Gungsuh, GungsuhChe, Haettenschweiler, Harrington, Impact, Informal Roman, IrisUPC, Iskoola Pota, JasmineUPC, KaiTi, Kalinga, Kartika, Khmer UI, KodchiangUPC, Kokila, Lao UI, Latha, Leelawadee, Levenim MT, LilyUPC, Lucida Bright, Lucida Console, Lucida Fax, Lucida Sans Unicode, MS Gothic, MS Mincho, MS PGothic, MS PMincho, MS Reference Sans Serif, MS UI Gothic, MV Boli, Magneto, Malgun Gothic, Mangal, Marlett, Matura MT Script Capitals, Meiryo UI, Meiryo, Microsoft Himalaya, Microsoft JhengHei, Microsoft New Tai Lue, Microsoft PhagsPa, Microsoft Sans Serif, Microsoft Tai Le, Microsoft Uighur, Microsoft YaHei, Microsoft Yi Baiti, MingLiU, MingLiU-ExtB, MingLiU_HKSCS, MingLiU_HKSCS-ExtB, Miriam Fixed, Miriam, Mongolian Baiti, MoolBoran, NSimSun, Narkisim, Niagara Solid, Nyala, PMingLiU, PMingLiU-ExtB, Palace Script MT, Palatino Linotype, Papyrus, Perpetua, Plantagenet Cherokee, Playbill, Raavi, Rockwell, Rod, Sakkal Majalla, Script MT Bold, Segoe Print, Segoe Script, Segoe UI Light, Segoe UI Symbol, Segoe UI, Shonar Bangla, Showcard Gothic, Shruti, SimHei, SimSun, SimSun-ExtB, Simplified Arabic Fixed, Simplified Arabic, Snap ITC, Sylfaen, Symbol, Tahoma, Times New Roman Baltic, Times New Roman CE, Times New Roman CYR, Times New Roman Greek, Times New Roman TUR, Times New Roman, Traditional Arabic, Trebuchet MS, Tunga, Utsaah, Vani, Verdana, Vijaya, Vladimir Script, Vrinda, Webdings, Wide Latin, Wingdings
Next time could be:
fontList-- Agency FB, Aharoni, Andalus, Angsana New, AngsanaUPC, Aparajita, Arabic Transparent, Arabic Typesetting, Arial Baltic, Arial Black, Arial CE, Arial CYR, Arial Greek, Arial TUR, Arial, Batang, BatangChe, Bauhaus 93, Bell MT, Bodoni MT, Bookman Old Style, Broadway, Browallia New, BrowalliaUPC, Calibri Light, Calibri, Californian FB, Cambria Math, Cambria, Candara, Castellar, Centaur, Century Gothic, Colonna MT, Comic Sans MS, Consolas, Constantia, Copperplate Gothic Light, Corbel, Cordia New, CordiaUPC, Courier New Baltic, Courier New CE, Courier New CYR, Courier New Greek, Courier New TUR, Courier New, DFKai-SB, DaunPenh, David, DilleniaUPC, DokChampa, Dotum, DotumChe, Ebrima, Engravers MT, Eras Bold ITC, Estrangelo Edessa, EucrosiaUPC, Euphemia, FangSong, Forte, FrankRuehl, Franklin Gothic Heavy, Franklin Gothic Medium, FreesiaUPC, French Script MT, Gabriola, Gautami, Georgia, Gigi, Gisha, Goudy Old Style, Gulim, GulimChe, Gungsuh, GungsuhChe, Haettenschweiler, Harrington, Impact, Informal Roman, IrisUPC, Iskoola Pota, JasmineUPC, KaiTi, Kalinga, Kartika, Khmer UI, KodchiangUPC, Kokila, Lao UI, Latha, Leelawadee, Levenim MT, LilyUPC, Lucida Bright, Lucida Console, Lucida Fax, Lucida Sans Unicode, MS Gothic, MS Mincho, MS PGothic, MS PMincho, MS Reference Sans Serif, MS UI Gothic, MV Boli, Magneto, Malgun Gothic, Mangal, Marlett, Matura MT Script Capitals, Meiryo UI, Meiryo, Microsoft Himalaya, Microsoft JhengHei, Microsoft New Tai Lue, Microsoft PhagsPa, Microsoft Sans Serif, Microsoft Tai Le, Microsoft Uighur, Microsoft YaHei, Microsoft Yi Baiti, MingLiU, MingLiU-ExtB, MingLiU_HKSCS, MingLiU_HKSCS-ExtB, Miriam Fixed, Miriam, Mongolian Baiti, MoolBoran, NSimSun, Narkisim, Niagara Solid, Nyala, PMingLiU, PMingLiU-ExtB, Palace Script MT, Palatino Linotype, Papyrus, Perpetua, Plantagenet Cherokee, Playbill, Raavi, Rockwell, Rod, Sakkal Majalla, Script MT Bold, Segoe Print, Segoe Script, Segoe UI Light, Segoe UI Semibold, Segoe UI Symbol, Segoe UI, Shonar Bangla, Showcard Gothic, Shruti, SimHei, SimSun, SimSun-ExtB, Simplified Arabic Fixed, Simplified Arabic, Snap ITC, Sylfaen, Symbol, Tahoma, Times New Roman Baltic, Times New Roman CE, Times New Roman CYR, Times New Roman Greek, Times New Roman TUR, Times New Roman, Traditional Arabic, Trebuchet MS, Tunga, Tw Cen MT Condensed Extra Bold, Utsaah, Vani, Verdana, Vijaya, Vladimir Script, Vrinda, Webdings, Wide Latin, Wingdings