p.s. Just to make clear what this list is for:

This isn't a list of all the hashtags people should use, because most of them are obvious and don't need a guide. Something like #Gardening is obvious and there's no need for anyone to tell you about it.

The point of this list is for unusual tags which aren't obvious. Things like #LichenSubscribe or #Florespondence aren't tags you could guess the existence of, you would have to be told about them. That's the point of this list.

You seem to be missing #dafaidodon for the sheep of Mastodon. 🐑🐑🐑 What fedi account is complete without following that! 😊

Edit: yes, that should be #defaidodon. 😊

I suggest adding those music oriented one

#ThursdayFiveList
#TuneTuesday
#JpopFriday

Here are some that have quite a bit of traction with those I follow (and who follow me.) Not that you asked 😉

#MacroMonday
#MonochromeMonday
#MosaicMonday
#MountainMonday

#TextureTuesday
#TrainTrackTuesday

#WildlifeWednesday

#ThrowBackThursday

#FernFriday
#FossilFriday
#FungiFriday

#InsectSaturday
#InsektenSamstag
#SaturdayScenery

#SunsetSunday
#SunriseSunday

Nice. I have wanted this list for ages!

A couple ND inclusive suggestions:

-ActuallyAutistic – The *author* of the post with this hashtag is autistic (self-id is fine, it's not about gatekeeping autism). Not meant to be used by parents or caregivers to describe autistic people, even if they really really feel they should be able to. Protip: use like a signature, not an adjective describing someone, to make it easier to guess if you're using it to identify yourself or misusing it. OK, it's a really badly named hashtag but it's what we're stuck with.
-Autistic – The correct way to describe an autistic person if you want to use a hashtag as an adjective.
-AskingAutistics – How to ask an autistic person a question about autism. Not to be used to get info on a random topic like autism is a public help desk.

this is very cool

and i hope my #ThisIsSoStupidButItMadeMeLaugh is easy to understand, even if it only tickles my funny bone

Didn't see ThreeGoodThings - individuals posting 3 positive things from their day

Also the daily games - Rogule, Tradle, Worldle, Wordle, CluesBySam, etc

No #HootinTootinTuesday on the list?

This is a list of my other favorites. There is a bit of duplication with your list, but there's definitely some here that you missed:

universeodon.com/@AnneTheWrite…

Awesome list, thank you!

+ #Astrodon for all things astronomy and space.

I have a suggestion for a non-obvious hashtag that I love to follow

#特に意味をなさない猫の計測
(Measurement of cats that do not make sense in particular) 😹

There are several #hashtags that celebrate wetlands in specific months:

#Fenuary (fens/February)

#MarshMadness (marshes/March)

#Swamptember (swamps/September)

#Bogtober (bogs/October)