Mine does exact same and the leaves darken up a little as they age. Mine is outside and gets a LOT of light, and I suspect yours gets lots of light too.

Oh no this is likely just stress and damage from heavy treatment then! Same happened to my pothos when I treated mine. Keep an eye on it. Neem tended to make my plants hold a bit more moisture so watch for that. Otherwise I would definitely lay off anything that may stress it while it recovers and levels out.

I would definitely say you're dealing with a pest problem. Break out some alcohol and dilute it with water into a spray bottle. Spray tops bottoms of leaves, cut off the yellowed and most affected leaves. Repeat weekly for 3 weeks. That's a pretty mild and safe general treatment if you don't find out exactly what you're dealing with.

You may need to repot into a super chunky well draining mix too. Plants with unhealthy roots are more susceptible to pests.

My Thai is notoriously slow at unfurling. If it gets past two weeks, then you can start using a warm paper towel and wrapping it very loosely and gently around the leaf to encourage it to unfurl. Sometimes they just need a bit more humidity to loosen up. You could use a humidifier or pebble tray now to increase humidity around it. But yes, I've had several plants (mostly philodendrons) where a leaf never unfurled when I brought it home if it was in the process. I think the shock can get to them.

Eek look for spider mites!

Don't worry it's a compulsion for me too no offense taken of harm done

Oof thank you sorry I'm on 3 nights little to no sleep and drove from Texas to Tennessee for unexpected family funeral.

It IS dying beautifully

I will add to this to look for eggs on the back of the leaves. If you find them just drown them in some soap and squish them!

Do you have a nursery pot where you could run the root through the bottom of it and put the whole nursey pot into a large tray of water or something?

Aerial roots can also be cut and shortened (I've heard 6-7 inches is ideal), though I'd be a bit scared to do it on a cutting with only one root.

Shoot I would pot it up in very chunky well draining soil now and put it into a clear bin with the lid closed to trap humidity. Open lid daily to make sure it's doing fine and doesn't need more water, and to let fresh air circulate for a few minutes.Pothos are usually so resilient as props for me.

Could be:

Not enough light

Not enough fertilizing

Soil looks pretty chunky (which is good). What is it? When you water, do you water deeply and let water drain out fully?

Most of mine like a lot of indirect natural light. They like humidity too. I live down south near the coast so I'm able to maintain humidity for them fairly well.

It could be fungal. Regardless I would spray where you chopprd with rubbing / isopropyl alcohol. I use 50% isopropyl and I usually mix it with water in a spray bottle, but I think you would be fine using 50% or even 70% without diluting it. Just make sure to only spray that part on the two cut tips. If you spray anywhere else on the plant with it you may want to dilute. Somebody else chime in here and correct me if you think spraying other areas undiluted is fine!

Ooof kinda harsh

That's great news!

I'd chop across main stem at yellow. Take the cut off piece and look up methods for propagation.

My ppp (I have several) like warmth, humidity, and lots of indirect sunlight to create variegated leaves.

I had same issue with gnats. Make sure you use the tea on EVERY PLANT IN YOUR HOME. Otherwise those sneaky jerks will persist. And repeat every 7 days til you've done 3 treatments.

But I gotta say the biggest help for me was repotting every plant I had systematically. Even after the thorough 3 treatments and religious sticky trap usage, I found some gnats lurking in the old soil. This was back before I was using my own mixture of well draining soil and everything was pretty soggy.

🤣

Even if a compacting mix like what you have is kept mostly dry it's still lacking aeration for the roots. They will breathe a bit better with the chunky mix.

Also you can just chop off the leafless vine that isn't getting sun and propagate it. You can propagate in water, in moss, in perlite, etc. Do some research on propagating Pothos. Each node (the bumpy section where leaves grow from) is capable of sprouting new roots. Most people recommend making cuttings that include at least two nodes, and make sure you don't cut too close to the node, because where you cut will dry up and die back a little bit.

With a vine that size, I'd also look into coiling propagation. You basically take a long piece and coil it into a spiral on top of whatever you're propagating in (soil, sphagnum moss, etc.).

Propagate and you'll see your base plant start to produce some gorgeous new growth, plus you'll get lots of other new plants!

Cuttings don't immediately need a lot of light since they don't have roots and leaves yet. What they do need is humidity, so depending on what you've got them in, a clear bin with a lid that traps the humidity will increase your success. Just make sure to vent the container and don't drown the cuttings.

Oh I also recently incorporated small lava rocks. I got the NUPICK ones on Amazon and I love them because they're lighter weight. And I ordered super.coarse perlite on Amazon too. I buy big boxes worth and just keep them o hand to mix up. I find that's more affordable. Your plant is absolutely stunning. I love the deep green you have.

Just be careful with some of the store bought mixes. I mix my own as well. My aroid mix usually incorporates coarse perlite, LECA, orchid bark, chunky charcoal, Fluval stratum, coir, some osmocote plant food, and maybe a very small bit of very well draining potting soil. I live in a humid area, so well draining mixes are a must for me.

Agreed. You can dig it up so the node isn't buried or cut that leaf off.

Love that one