But if the point is to remember it, then you should use the security from length of series of 5+ random words. It’s easier to remember, write down, and type. All great characteristics of a master passphrase.
There's just a theoretical weakness since the base word lists are usually public knowledge and bruteforcers could (and probably already have) optimize for that.
The advantages of a passphrase outweigh though as you mentioned. An attacker would first need your repo anyway.
Also, you don't need to write it down correctly, if you remember what's the missing or different or fake bit. And you can write down a few decoy ones next to it. Or have it in two different places. Lots of room for obfuscation along with some good old fashioned physical security on where you store the note. And the backup note off-site, if you're that kind of person.
Hell, just make some extra decoy ones just for fun and practice.
My strategy for this is to have a second password manager available on a couple old devices, accessed with biometrics (fingerprint in this case), and only the master password saved within it.
I considered saving it within the main manager itself, since I have devices where I can use biometrics rather than password, but that feels like a bad idea.