I'm just some rando on the internet, but what makes you think its a fungal issue? Admittedly I don't know any of the specifics of your grow, but the upward curling leaf tips might suggest the light is too close and/or hot. Also, can you rule out calcium deficiency? it can look a lot like septoria esp if there is a Mg deficiency concurrent, which can produce the darker spots in addition to the browning between veins. best of luck mate, while I wish I could be more help, too much light+calcium def is what it looks most like to me, but it wouldn't be the first time I was wrong. Hopefully some others will chime in on their thoughts.
Well I had that issue before apparently from what I was told but there’s not a lot of yellowing at all from what I see. Humidity is at 50% and temp is 73(lights off) - 83(lights on) Soil last I checked was around 6.5 PH.