OP, this is 100% holtodrilus truncatus, a branchiobdellidan ectosymbiont. No planaria and other medications used to target gill worms and flat worms won‘t work effectively (have tried myself). The only treatment that I know of is salt (NaCl). [Here](https://aquariumbreeder.com/holtodrilus-truncates-parasites-in-shrimp-keeping-hobby/) you can find a description of the organism. There is a scientific investigation from 2016 ([Kaoruko Tanaka et al.](https://pubmed.ncbi.nlm.nih.gov/27032680/)) showing that increasing salinity to 0.5% (5g pure Aquarium salt per liter aquarium water) over more than a week kills the worm quite effectively.
I am currently battling with them myself and am trying this approach. Be careful though this will sharply raise your nitrite levels within days. I will make a post detailing it once I have finished it. You can also treat individual shrimps with salt baths. The details regarding how this is done, you will find behind the first link.
UPDATE: I bought aquarium salt and decided to treat the whole tank, as i bought all the shrimp from the same place and figured they could all be infected. I dripped salt water until .5salinity. I will update again in a week to let yall know if the treatment worked! Thank you all so much for your help!
My crayfish got this, a salt bath always did the trick, but shrimp aren’t as hardy so you’ll probably have to go a gentler route with just salt added Aquarium
When I worked in an aquarium store I used paraguard and it worked, it’s not technically shrimp safe though but it worked to deworm entire shipments of shrimp.
LaFluffy 
OP, this is 100% holtodrilus truncatus, a branchiobdellidan ectosymbiont. No planaria and other medications used to target gill worms and flat worms won‘t work effectively (have tried myself). The only treatment that I know of is salt (NaCl). [Here](https://aquariumbreeder.com/holtodrilus-truncates-parasites-in-shrimp-keeping-hobby/) you can find a description of the organism. There is a scientific investigation from 2016 ([Kaoruko Tanaka et al.](https://pubmed.ncbi.nlm.nih.gov/27032680/)) showing that increasing salinity to 0.5% (5g pure Aquarium salt per liter aquarium water) over more than a week kills the worm quite effectively.
I am currently battling with them myself and am trying this approach. Be careful though this will sharply raise your nitrite levels within days. I will make a post detailing it once I have finished it. You can also treat individual shrimps with salt baths. The details regarding how this is done, you will find behind the first link.
Quarantine her asap just to be safe, and in the process you may be able to get a closer look at it.
UPDATE: I bought aquarium salt and decided to treat the whole tank, as i bought all the shrimp from the same place and figured they could all be infected. I dripped salt water until .5salinity. I will update again in a week to let yall know if the treatment worked! Thank you all so much for your help!
My crayfish got this, a salt bath always did the trick, but shrimp aren’t as hardy so you’ll probably have to go a gentler route with just salt added Aquarium
Looks like leeches. Fenbendazole should take care of em.
When I worked in an aquarium store I used paraguard and it worked, it’s not technically shrimp safe though but it worked to deworm entire shipments of shrimp.
Possibly scutariella. I’d try a quick, strong salt dip or two, most parasites hate salt.
https://www.amazon.com/Genchem-Planaria-Shrimp-Killer-Planted/dp/B07M683JK4
or
https://www.amazon.com/Benibachi-Planaria-Zero-20g/dp/B00E877CPW
or really any dewormer
https://www.amazon.com/Panacur-Canine-Dewormer-1-gram/dp/B00028ZLD6
It almost looks like leafy bits from the plant shrimpy is on? But im not sure