Need Help Saving Weeping Moss And Fissidens Fox

My weeping moss and fissidens fox are turning browner and browner every day, im trying to figure out how to save them.

Here is the current picture of the tank, you can see the browning at the moss on top and fox at the base of the tree and also at the monte carlo on the floor: https://imgur.com/a/bRUIjOP

Here are my questions:
Is there a way to tell if plant is browning(dieing) or if its from brown algae? ( see attached images )
Can there be too much light for low-mid light plants which could cause them to die? Like the weeping moss at the top?
Does indirect light or direct light from a led light matter?
Is flourish Excel moss safe?
Weeping moss and fissdens fox browning, how can I figure out what is causing it?

Detail for those interested
Tank Specs:
7.9 fluvial ebi nano tank
Black Diamond blasting abrasive– inert substrate
Chichiros 25 watt rgb, dimmed to be approx. 16 watt total. On for 12 hours per day to create enough algae for otos.

Dosing:
2 flourish tabs in soil – replaced every 4-6 months
1/5 cap full of flourish liquid once a week
Flourish excel a few drops daily.

Cycle:
Tank about 1 -1.5 months old. Dosed 4ppm ammonia, then used tetra safe start to cycle. Tested daily and its definitely fully cycled. I recently added in plants + oto catfish.

Residents that matter to this posting:
Flora:
Fissidens Fox
Vesicularia Ferriei Weeping Moss
Fauna:
oto catfish
Soon to house blue dream shrimp

Thanks in advance for any help!

 

First, thank you so much for replying and for such a detailed answer, it was immensely helpful.

For now i stopped excel since it seems like there is a 50/50 shot it'll kill the moss or it wont. Ive been googling for hours and everyone has different opinions, im figuring its better to be safe than sorry and just stop using it. For flourish comprehensive, you are correct this is what i was using. Do you have any recommendations on commonly available ferts with macro nutrients that would balance out the flourish comp? I can handle looking up if they are shrimp safe or not, just hoping you can point me in the right direction. The moss is even more brown today and i cant have c02 in the tank either since its a shrimp breeding tank, so im hoping that dosing more fertilizer is the answer.

The substrate is fully intert but i do have flourish tabs in there.

 

Hi Everyone,

To update those who commented, as well as any who may come across this thread in the future, i figured out the solution.

1. Change of fertilizer, i changed from flourish comprehensive to thriveS and the plants instantly started recovering, especially the weeping moss which started to grow.
2. Stopped dosing flourish excel, it was killing both even when not placed directly on top of the plants
3. Moved the light further away from the moss, once i did this not only did new growth continue but the brown of the plant started to come back to life. I guess it doesn't like intense light, which kind of sucks since its at the top of the tree.

Thanks for everyone's contribution and hope this helps someone in the future who may have the same plants!

Thanks,
Suneel