HELP! Strawberry Banana deficiency?

[Sunlight]

Hello , the center of leaves are starting to fade, pictures are from this morning, any clues on what the deficiency is.
It’s a 20 gallon fabric container With Sub cool super soil in ground now due to height concerns leaves affected are At 1/3 From bottom of plant , possibly leeched or it didn’t cook properly? See pics

[Sunlight]

Any help on figuring out deficiency before it get to far would be greatly appreciated

[SoOrbudgal]

OK so you cut the bottom out of pot and buried it in a hole? Yes that red bark mulch may be the cause or could be beginnings of TMV read up look at it just in case. Or could be that mulch is it cedar? Rake it away from the hole.?

[Rwise]

As wood rots it takes the N from the soil, when it decays the N is turned loose.
Root/PH issue is what I see.