Hopefully someone here knows what i'm doing wrong before I pull my hair out

-3 gallon cube running for 4 months now, constant 80F, 20% water changes every 7-14 days, 3x Swordplant 1x Moneywort Multiple x floaters

-Only has 1 betta

-planted aquarium substrate approx 2-2.5"

-LED plant grow light

-has CO2 injection, diffused through glass/ceramic diffuser at 2 bubbles per second. Drop checker is always the proper bright green colour

-dose each of the 3 swordplants with 1x Seachem flourish tab by the roots

-liquid doses of Seachem flourish iron every 7-10 days

All 4 plants have been in the tank since it was set up early May, Moneywort always has/still is growing like nuts and has multiple 1ft stalks growing out of the tank. Swords grew well until early July when I set up the CO2 injection and used the fertilizers, since then many random leaves will go brown halfway, get the yellow line then proceed to completely go brown and die yet some leaves will constantly be healthy. They're planted properly with the crown exposed above the substrate, have massive roots, and get proper fertilizer tabs. wtf am I doing wrong? The picture is after cutting 5-6 brown leaves last night right at the Crown. The far right side leaf pointing up already looks a pale yellow and looks like it's ready to brown out too

All I can think of is the light is too weak due to floating plants/tannins, I ordered the Fluval plant grow light that has more power which is on it's way but otherwise i'm open to suggestions

Plants