Yellowing / Browning leaves

[MSchep]

Just wanting to get some input from this amazing community on what I might be dealing with here. These are a few leaves on my two Orange Oxheart plants, growing like crazy in an Earthtainer. I had all new mix this year, so I don't think this would be anything soil borne. Aside from a few of the leaves looking like this, the rest of the plants are doing great. Already almost 6ft tall, and probably 2-3 dozen fruit developing quickly.

I'm sure this is something common, but I just haven't experienced it yet, so can't ID it yet. Two pics of the same leaf, front and back.

Thanks in advance for the guidance!!